CALCULATION POLICY – ADDITION AND SUBTRACTION Foundation Stage Aim by end of year: - All can move (count on or back) up to 10 spaces on a number track. -Some can add two 1 digit numbers showing method used. -All can subtract small numbers by taking away using apparatus. -Some can discuss difference mathematically . Addition Subtraction Make own marks or tallies to record numbers. Begin to relate addition to combining two groups of objects and counting on. Adult to model number sentences in context. Begin to relate subtraction to taking objects away from a group and counting what is left. Find own way of recording for subtraction e.g. cross-outs. Begin to record numbers and number sentences, when ready. 3 + 2 = 5 Select two groups of objects to make a given total e.g. Find dominoes with 6 dots on. Adults scribe number sentences. ◦ 2+4=6 1+5=6 Adults model use of number tracks and number lines. 1 2 3 4 5 6 7 8 9 10 4+2=6 Find own way of recording for addition. Using pictures, symbols, apparatus e.g. 3 5 2 5 Sing nursery rhymes and simple songs. Solve practical problems in a real or role play context and talk about own ideas, methods and solutions. E.g. Sarah wants 3 grapes and you want 4 grapes. How many grapes do I need altogether? Year 1 Aim by end of year: -All can add two 1 digit numbers -Some can add a 1 digit number to a 2 digit number Showing method used. -All can count Relate addition to combining two groups and counting on and record in a number sentence using + and = signs. Record addition by: - showing jumps on prepared number lines - drawing own number line e.g. 6 + 5 = 11 6 7 8 9 7–2=5 Children record number sentences related to practical work, when ready. Experience subtraction in the context of counting back along a number track e.g. jumping backwards two jumps along a floor number track game. Adults model use of number tracks and number lines. Use a number track to find one more than a number. Say the number one more than when playing a board game. Experience addition as counting on, e.g. rolling a dice and moving along a number track when playing snakes and ladders. Children to work practically with bead bars and bead strings. Number tracks and number lines to be available for children to use in free flow activities. 3 and 2 Adults to model recording. (After practical work, in context and in conjunction with apparatus). 10 Page 1 11 1 2 3 4 5 6 7 8 9 10 6–2=4 Use a number track to find one less than a number. Children to work practically with bead bars and bead strings. Number tracks and number lines to be available for children to use in free flow activities. Start to develop the concept of difference by comparing objects by the number in two sets or in the context of measures and saying if they are the same or different e.g. number of sweets in different size jars. or when playing with cars make two rows and discuss that the row of 12 cars is longer than the row of 8 cars. “Can you make them the same length? How?” Sing nursery rhymes, involving something being taken away in each verse e.g. 5 little men in a flying saucer. Solve practical problems in a real or role play context and talk about own ideas, methods and solutions e.g. In a play shop put 10 pennies in a purse, pay for something and say how much money they have left Relate subtraction to taking away by counting back and as counting on and record in a number sentence using the – and = signs. Record simple subtraction in a number sentence using the – and = signs e.g. There were 8 cakes on a plate. Mary ate 3 of them. How many were left? 8–3=5 May 2009 CALCULATION POLICY – ADDITION AND SUBTRACTION back on a number line to subtract 1 digit numbers from a 1 or 2 digit number. -Some can count on when the difference is small. Addition Subtraction Using the empty number line to add 10 to a single digit number. e.g. 8 + 10 = 18 +10 Use objects to develop idea that the number of objects started with and those taken away can be represented by a subtraction calculation. 8 18 Use a number line to add a pair of single digit numbers to bridge through 10 e.g. 8 + 5 = 13 Model this strategy. 2 3 +2 +3 8 10 13 (see Framework – section 5 p.40) Shows 9 + 1 + 5 = 15 or 9 + 6 = 15 Bridge through a multiple of 10 e.g. add a single digit to a teen’s number bridging through 20. 18 + 5 = 23 2 10 15 Or record as: 18 + 5 = 18 + 2 + 3 = 20 + 3 = 23 3 +2 18 +3 20 23 1 2 3 4 5 6 7 8 9 10 11 12 What is the difference between 5 and 12? on) – marked line 1 2 3 4 Represent number line calculations in a number sentence e.g. +1 +5 9 Use a marked or empty number line to count back (take away) or to count on (find the difference) e.g. 12 – 7 (counting back) - marked line 5 6 (counting 7 8 9 10 11 12 What is the difference between 5 and 12? (counting on) – empty line 5 12 Children need to begin to understand when it is sensible to count back e.g. 18 – 5 13 14 15 16 17 18 And when it is sensible to count on e.g. 18 – 13 13 14 15 16 17 18 Say the number that is one more than any given number and ten more than a multiple of ten. Add 9 by adding 10 and subtracting 1. Say the number that is 1 less than any given number or 10 less than a multiple of 10. Find the difference between two numbers by comparing them using apparatus or on number lines e.g. What is the difference between 4 and 7? 17 + 9 With cubes: + 10 17 26 -1 Partition numbers using place value cards 1 7 How many more? 27 10 7 17 = 10 + 7 And use calculator to confirm that numbers such as 57 are made up of 50 and 7 to develop their understanding of place value. Be able to complete number sentences where a missing number is shown by a symbol e.g. 5+2= ∆ ∆ =5+2 5+∆=7 7=∆+2 ∆ + 2 =7 7=2 +∆ etc. Generate equivalent calculations for given numbers and record e.g. 6 =2 + 4 = 1 + 5 = 3 + 3 Page 2 or on two number lines: 4 7 or on one number line: 4 7 Be able to complete number sentences where a missing number is shown by a symbol e.g. 6-2=∆ ∆ =6-2 6-∆=4 4=∆-2 ∆ -2=4 4=О-∆ etc. May 2009 CALCULATION POLICY – ADDITION AND SUBTRACTION Year 2 Aim by end of year: -All can add 1 digit number to a 2 digit number. -Some can add two 2 digit numbers showing method used. -All can use a number line to subtract 2 digit numbers -Some can subtract numbers that cross 100. Addition Subtraction Derive and recall pairs of numbers with a total of 10 and addition facts for totals to at least 5. Solve simple problems explaining methods and reasoning orally or in pictures in the context of measures or money. Use the language of addition accurately. Read 19 + 15 = 34 as nineteen add fifteen equals 34. Decide the best strategy for addition: put the larger number first and count on; look for numbers that total 10 or 20; partition and recombine. Use prepared number lines then progress on to drawing own empty number lines to: e.g. Solve simple problems involving subtraction in the context of measure or money explaining reasoning orally or in pictures e.g. This bottle holds 5 cups of water but this bottle holds 7 cups. How much more is in the bigger bottle? count in tens 23 + 20 +10 +10 23 33 Use marked, partly marked or empty number lines to count back (take away) or to count on (find the difference) – as Y1. Understand when it is sensible to count back and when to count on. e.g. 93 – 5 (count back) 93 - 88 (count on) 88 43 count in multiples of ten +20 27 + 20 93 Use number lines or jottings to count back. 76 – 15 27 47 -5 To add tens and units by partition second number (not crossing the tens or hundreds barrier) using different methods of recording: Use language of subtraction accurately. Read 16 – 4 = 12 as sixteen subtract 4 equals twelve. number line 45 + 13 = +10 +3 -10 61 66 76 Record in number sentences : 76 – 10 = 66 66 – 5 = 61 Bridge through multiple of 10 when counting back. 45 55 Record in number sentences 45 +10 = 55 55 + 3 = 58 -4 Lead to partitioning - second number only. 35 + 20 + 3 55 + 3 = 58 50 + 8 = 58 Bridge through a multiple of 10, explaining method 16 + 7 = 23 4 16 +4 46 -1 50 -20 51 71 Record in number sentences: 71 -20 = 51 51 – 1 = 50 50 – 4 = 46 Subtract 1 or 10 from any given number. using drawing = 50 35 + 23 =8 71 – 25 not using number line, partitioning both numbers 35 + 23 30 + 20 = 50 5+ 3=8 50 + 8 = 58 58 3 Count on to the nearest 10. 23 – 18 = 5 +2 +3 18 20 23 Develop into calculations that count on in three jumps. +3 20 Relate finding a difference to subtraction. Understand difference is the same as subtraction and work out small differences by counting on. 23 or record as 16 + 7 = 16 + 4 + 3 = 20 + 3 = 23 91 – 65 (counting on) +5 65 Page 3 +20 70 +1 90 = 26 91 May 2009 CALCULATION POLICY – ADDITION AND SUBTRACTION Addition Subtraction Add 1 or 10 to any given number. Add 19 or 21 by adding 10 and adjusting. e.g. 27 + 19 = 27 + 20 -1 = 47 -1 = 46 Using partitioning (second number only) -not crossing 10 -crossing 10 48 – 23 = 48 – 20 – 3 73 – 25 = 73 -20 - 5 = 28 – 3 = 53 - 5 = 25 = 48 Or using empty number line +20 27 46 -1 47 Subtract 9 or 19, by subtracting 10 or 20 and adjusting. E.g. 45 – 9 = 45 – 10 +1 = 35 +1 = 36 0r using empty number line -10 35 Year 3 Aim by end of year: -All children add two 2 digit numbers. -Some can add 2 and 3 digit numbers, showing method used. -All children should be able to use a method to subtract 2 and 3digit numbers. -Some should be able to use expanded decomposition as shown. Use knowledge of facts to identify missing numbers in sentences. 9 + ∆ = 13 ∆+ 4 = 13 ∆ + ◊ = 13 40 + = 100 +200 = 400 etc Extend to 3 numbers: and: 5 + ∆ + 4 = 13 13 + 5 = ∆ + 10 50 + ∆ + 3 = 73 12 + ∆ = 14 + 4 etc 13 = ∆+ ◊+ 3 etc Generate equivalent calculations for a given number. e.g. 20 20 = 10 + 10 = 11 + 9 etc Derive and recall all addition facts for each number to at least 10, all pairs which total 20 and multiples of 10 with totals up to 100. Solve problems involving addition in contexts of measures or pounds and pence explaining methods and reasoning orally and where appropriate in pictures and writing. Use of mathematical vocabulary is more precise. Develop methods for adding two digit and three digit numbers by partitioning second number only. 246 + 87 246 + 80 + 7 or 246 + 7 + 80 leading to: = 756 + 20 +7 = 776 + 7 = 783 Use knowledge of place value and partitioning of three digit numbers to develop written methods for addition of two and three digit numbers using expanded methods of recording. 375 + 67 300 70 + 60 300 130 5 7 12 = 442 Solve problems involving subtraction in contexts of measures or pounds and pence explaining methods and reasoning orally and where appropriate in pictures and writing e.g. In the sales my coat was reduced from £15.50 to £12.99. What was the difference in price? Use of mathematical vocabulary is more precise. Use a number line to count back alongside an informal written method. 246 -47 -7 199 -40 206 246 246 – 40 = 206 206 - 7 = 199 Begin to record calculations in preparation for an efficient standard method. Expanded decomposition (see Framework – section 5 p45) E.g. 81 – 57 leading to: 81 - 57 Page 4 45 +1 Use knowledge of facts to identify missing numbers in number sentences. 13 - ∆ = 9 ∆-4 =9 ∆ - ◊= 9 etc Extend to: 13 + 5 = ∆ - 10 etc 356 + 427 = 356 + (400 + 20 + 7) First step: 356 + 400 =756 756 + 20 = 776 776 + 7 = 783 36 81 and 1 = 70 and 11 50 and 7 = 50 and 7 20 and 4 = 24 May 2009 70 1 80 1 50 7 20 4 = 24 CALCULATION POLICY – ADDITION AND SUBTRACTION Addition 67 + 24 80 11 91 83 + 42 120 5 125 Subtraction Add most significant digits first. Add mentally from top. This leads onto most significant digits first. Bridge through a multiple of 10 to add, explaining method e.g. 68 + 7 2 5 = 68 + 2 + 5 = 70 + 5 = 75 Add 1, 10 or 100 to any given number. Add a near multiple of 10 to a two digit number and show on a number line e.g. 45 + 28 +30 45 73 -2 75 Count up when the difference is small (complementary addition) (Framework - Section 5 p45) e.g. 216 -187 +13 +16 = 29 187 200 216 216 - 187 13 to make 200 16 to make 216 29 Subtract 1, 10 or 100 from any given number. Subtract a near multiple of 10 from a 2-digit number, explaining the method used e.g. 96 – 39 = 96 – 40 +1 = 56 +1 = 57 or -40 56 Apply understanding of inverse relationship between addition and subtraction to generate pairs of statements to find unknowns in number sentences. 4 + ∆ = 33 33 – 4 = Use knowledge of number facts to find unknowns. 347 + ∆ = 447 Use 3 numbers e.g. 10 + ∆ + 50 = 100 ∆ + ◊ + O = 100 Recall pairs of numbers with totals of 100 and addition facts for totals to at least 20. Solve problems explaining methods and reasoning orally and where appropriate in pictures and writing, in the context of measures money and time. Year 4 Aim by end of year: -All can use an efficient written method to add and subtract 2 and 3 digit whole numbers and £.p. but continue to use counting up method where appropriate. Note: ‘compact’ method is not appropriate for adding two 2-digit numbers – this is a mental method. Use symbols and missing numbers:Continue to develop as in Y1, 2 and 3 but with appropriate numbers. Develop use of empty number lines, partitioning and other informal recording methods developed in Y1,2 and 3 to support and explain calculations where appropriate e.g. 146 +29 +30 146 175 -1 176 548 + 235 548 + 235 = 548 + 200 + 30 + 5 = 748 + 30 + 5 = 778 + 5 = 783 57 96 +1 Apply the understanding of the inverse relationship between addition and subtraction to generate pairs of statements to find unknowns in number sentences. ∆ - 15 = 19 19 – 15 =∆ Use knowledge of number facts to find unknown numbers. ∆ - ◊= 19 20 - ∆ - ◊= 5 etc Solve one and two step problems involving subtraction in contexts of measures money and time, explain methods and reasoning orally in pictures and writing e.g. The bus left school at 8.30 and arrived at the museum at 10.15. How long was the journey? Continue to use counting up (complimentary addition) method, with informal notes or jottings, when appropriate e.g. When subtracting from multiples of 100 or 1000 Finding a small difference by counting up e.g. 5003 – 4996 =7. (can be modelled using an empty number line or jottings) +4 +3 =7 4996 5003 To support or explain mental calculations e.g. 754 – 86 = + 14 + 600 + 54 = 668 +14 86 Page 5 5000 +600 100 +54 700 May 2009 754 CALCULATION POLICY – ADDITION AND SUBTRACTION Addition Subtraction Begin expanded method, adding least significant digit first 625 205 358 If children find + 48 + 176 + 973 this difficult go back to first 13 11 11 stage (see Y3) 60 70 120 600 300 1200 673 381 1331 Explaining the subtraction of the nearest multiple of 10 and adjusting (see Y2/3 examples) Teach expanded decomposition leading to compact decomposition. (see Framework – section 6 p50) - 754 86 - = 700 and 40 and 14 80 and 6 This leads to preparing for ‘carrying’ below the line (compact recording). (see Framework – Section 6 p48) To tens 625 + 48 673 1 to hundreds 783 + 42 825 1 Cross out the digit that has been carried, once it has been added in. 11 Extend to decimals as appropriate e.g. money knowing that the decimal points should line up under each other. Use knowledge of addition facts and place value to derive sums of pairs of multiples of 10, 100 or 1000. Solve problems explaining methods and reasoning. Year 5 Aim by end of year: -Most children are able to use compact method for addition and compact decomposition for subtraction, when appropriate, (numbers up to 10,000 and decimals) but should continue to use counting up method, where appropriate. Use symbols and missing numbers:Continue to develop as in Y1, 2, 3 and 4 but with appropriate number.s Develop use of empty number lines, partitioning and other informal recording methods to support and explain calculations where appropriate (including decimals). 125.64 + 56.7 125.64 + 50 + 6 + .7 175.64 + 6 + .7 181.64 + .7 182.34 50 6 0.7 125.64 = 600 and 140 and 14 80 and 6 tens and hundreds 367 + 85 452 175.64 181.64 Leading to: 754 - 86 600 = 700 600 1 50 4 80 6 60 8 = 668 7 '5 8 - 8 6 668 Extend to decimals as appropriate e.g. money knowing that the decimal points should line up under each other. Solve problems explaining methods and reasoning. Continue to use counting up (complimentary addition) method, with empty number lines, when appropriate e.g. When subtracting from multiples of 100 or 1000 Finding a small difference by counting up, or when bridging across a boundary by a small amount. e.g. 8006 – 2993 = 5013. (can be modelled using an empty number line or jottings) +7 +5000 +6 2993 3000 8000 8006 Using known number facts and place value to subtract e.g. 4.1 – 1.8 = 2.3 +0.2 +2.0 +0.1 182.34 - 2.0 4.0 4.1 to support or explain mental calculations to support or explain the subtraction of the nearest multiple of 10 or 100 then adjust e.g. 4005 – 1997 = 4005 – 2000 +3 = 2005 +3 = 2008 Page 6 = 668 Leading to: 1.8 Note: ‘compact’ method is not appropriate for adding two 2-digit numbers – this is a mental method. = 700 and 50 and 4 80 and 6 May 2009 CALCULATION POLICY – ADDITION AND SUBTRACTION Addition Subtraction Use compact (‘carrying’) method. See (see Framework – section 6 p49 – Method C) 587 3587 + 475 + 675 1062 4262 Continue to develop compact decomposition with different numbers of digits and decimals. Note: Children should understand the importance of lining up units digits under units digits, tens under tens etc. 11 111 HTU + HTU then ThHTU + ThHTU Children may need to return to expanded method when first carrying out addition of decimals - least significant digits first. Ensure that children know the importance of ‘lining up’ the decimal points particularly when adding mixed amounts e.g. 16.4 m. + 7.68 m. 16.4 + 7. 68 2 4 . 0 8m. 4 3 5 '7 6 4 .' 0 - 821. 6 4 942. 4 Children may need to return to expanded method when first carrying out subtraction involving decimal numbers. This reinforces understanding of place value, particularly with decimals. 1 1 Year 6 Aim by the end of Year 6: -All children should be able to use carrying method for addition and decomposition method for subtraction, accurately and reliably – when appropriate but should be able use counting up method, with jottings, where appropriate. Note: ‘compact’ method is not appropriate for adding and subtracting two 2digit numbers – this is a mental method Solve problems, explaining methods and reasoning orally and in writing. Solve problems, explaining methods and reasoning orally and in writing. Use symbols and missing numbers:Continue to develop as in earlier years but with appropriate numbers (including decimals) Develop use of empty number lines, partitioning and other informal recording methods developed in earlier years to support and explain calculations where appropriate (including decimals). Use compact (‘carrying’) method. As Y5, extend method to any number of digits and decimal places Use symbols and missing numbers:Continue to develop as in earlier years but with appropriate numbers (including decimals) Develop use of empty number lines, partitioning and other informal recording methods developed in earlier years to support and explain calculations where appropriate (including decimals). Continue to use complimentary addition, using an empty number line, informal notes or jottings when appropriate with appropriate numbers e.g. For those children who have not mastered compact method (see Framework – section 6 p49 Method C) or are unable to use it reliably, use expanded method, but teach again when appropriate. 0.5 – 0.31 +0.09 = + 0.09 + 0.1 = 0.19 +0.1 0.31 0.40 0.50 Subtracting the nearest multiple of 10,100, 1000 Subtracting from any multiple of 1000, 10,000 etc Solve problems explaining methods and reasoning orally and in writing. Page 7 i.e. where using decomposition would be very complicated. Continue to develop compact decomposition with different numbers of digits and decimals. Note: Children should understand the importance of lining up digits. May 2009