The Firs Primary School May 2015 PROGRESSION THROUGH CALCULATIONS FOR MULTIPLICATION MENTAL CALCULATIONS (ongoing) Doubling and halving Applying the knowledge of doubles and halves to known facts. e.g. 8 x 4 is double 4 x 4 Using multiplication facts Tables should be taught everyday from Y2 onwards, either as part of the mental oral starter or other times as appropriate within the day. Year 2 2 times table 3 times table 4 times table 5 times table 10 times table Year 3 2 times table 3 times table 4 times table 5 times table 8 times table 9 time table 10 times table Year 4 Derive and recall all multiplication facts up to 12 x 12 Years 5 & 6 Derive and recall quickly all multiplication facts up to 12 x 12. Using rounding Year 6 to use rounding strategy to help complete money problems, e.g. 4 x £9.99= 4 x 10 = £40 – (4 x 1p) = £39.96 Using and applying division facts Children should be able to utilise their tables knowledge to derive other facts. e.g. If I know 3 x 7 = 21, what else do I know? Page 1 of 14 The Firs Primary School May 2015 30 x 7 = 210, 300 x 7 = 2100, 3000 x 7 = 21 000, 0.3 x 7 = 2.1 etc Use closely related facts already known 13 x 11 = (13 x 10) + (13 x 1) = 130 + 13 = 143 Multiplying by 10 or 100 Knowing that the effect of multiplying by 10 is a shift in the digits one place to the left. Knowing that the effect of multiplying by 100 is a shift in the digits two places to the left. Partitioning 23 x 4 = (20 x 4) + (3 x 4) = 80 + 12 = 102 Use of factors 8 x 12 = 8 x 4 x 3 MANY MENTAL CALCULATION STRATEGIES WILL CONTINUE TO BE USED. THEY ARE NOT REPLACED BY WRITTEN METHODS. Page 2 of 14 The Firs Primary School May 2015 YR and Y1 (Stage 1) Children will experience equal groups of objects/ beads and will count in 2s and 10s and begin to count in 5s. They will work on practical problem solving activities involving equal sets or groups between different numbers. Page 3 of 14 The Firs Primary School May 2015 Y2 (Stage 2) Children will develop their understanding of multiplication and use jottings to support calculation: Repeated addition 3 times 5 is 5 + 5 + 5 = 15 or 3 lots of 5 or 5 x 3 Repeated addition can be shown easily on a number line: 5x3=5+5+5 5 0 1 2 5 3 4 5 6 7 5 8 9 10 11 12 13 14 15 and on a bead bar: 5x3=5+5+5 5 5 5 Commutativity Children should know that 3 x 5 has the same answer as 5 x 3. This can also be shown on the number line. 5 0 1 2 3 5 3 4 5 3 6 7 5 8 3 9 10 11 12 13 14 15 3 Page 4 of 14 3 The Firs Primary School May 2015 Arrays Children should be able to model a multiplication calculation using an array. This knowledge will support with the development of the grid method. 5 x 3 = 15 3 x 5 = 15 Page 5 of 14 The Firs Primary School May 2015 Y3 (Low Stage 3) Children will continue to use: Repeated addition 4 times 6 is 6 + 6 + 6 + 6 = 24 or 4 lots of 6 or 6 x 4 Children should use number lines or bead bars to support their understanding. 6 0 6 6 6 6 12 6 6 18 24 6 6 Arrays Children should be able to model a multiplication calculation using an array. This knowledge will support with the development of the grid method. 9 x 4 = 36 9 x 4 = 36 Children will also develop an understanding of Scaling e.g. Find a ribbon that is 4 times as long as the blue ribbon 5 cm 20 cm Page 6 of 14 The Firs Primary School May 2015 Using symbols to stand for unknown numbers to complete equations using inverse operations x 5 = 20 3 x = 18 x = 32 Partitioning (Secure Stage 3) 38 x 5 = 30 x 5 = 150 = 8 x 5 = 40 = 190 Page 7 of 14 The Firs Primary School May 2015 Y4 Children will continue to use arrays where appropriate leading into the grid method of multiplication. Partition- Grid method 14 x 6 = x 10 4 (6 x 10) + (6 x 4) 6 60 24 60 + 24 84 (Stage 4) Expanded column method for long multiplication TU x U Children will approximate first 23 x 8 is approximately 25 x 8 = 200 HTU 23 x 8 160 (20 x 8) 24 (3 x 8) 184 Pupils become more aware of place value issues with the layout of the partitioning already under relevant place value positions with pupils describing Page 8 of 14 The Firs Primary School May 2015 actual values of the digits in the columns. To begin partitioning process with the biggest number. Children who are secure with multiplication for TU x U should have little difficulty in using the same method for HTU x U. Short column multiplication – multiplication by a single digit HTU 2 23 x 8 184 To emphasise place value of digits within the sum, particularly when referring to numbers placed in columns larger than Units (i.e. 2 has a value of 20). It is imperative that partitioning understanding is secure by this stage of pupils’ multiplication knowledge. Children who are secure with multiplication for TU x U should have little difficulty in using the same method for HTU x U. HTU 3 5 346 x 9 3114 Page 9 of 14 The Firs Primary School May 2015 Y5 (Stage 4) Partitioning method HTU x U Children will approximate first 346 x 9 is approximately 350 x 10 = 3500 346 x 9= (300 x 9) + (40 x 9) + (6 x 9) = 2700 + 360 + 54 = 3114 Expanded column method for long multiplication TU x TU Children will approximate first 72 x 38 is approximately 70 x 40 = 2800 HTU 72 x 38 2100 (70 x 30) 560 (70 x 8) 60 (2 x 30) 16 (2 x 8) 2736 1 Children should describe what they do referring to the actual values of the digits in the columns. For example, the step that involves 2 x 30 should be described as ‘two multiplied by thirty’, not ‘two multiplied by three’, although the relationship 2 x 3 should be stressed. Children who are secure with multiplication for TU x TU should have little difficulty in using the same method for HTU x TU. Page 10 of 14 The Firs Primary School May 2015 Short column multiplication TU x TU 72 x 38 HTU Multiplication sums to begin with unit columns (8x2 and 8x7) with any carry overs placed above the sum. The second row of numbers are to start with 0 in the units column as each sum will incorporate the digit from the Tens column. 1 72 x 38 576 2160 2736 U.th x U Using similar methods, they will be able to multiply decimals with one decimal place by a single digit number, approximating first. Pupils must be secure with their understanding of place value when multiplying with decimal numbers, i.e. 0.9 x 3 = 2.7 can be completed using knowledge of 9 x 3. Consequently the answer has moved one place value to the right due to the movement of the 9 from the 9 x 3 sum to 0.9. e.g. 4.9 x 3 Children can approximate first 4.9 x 3 is approximately 5 x 3 = 15 U. t 2 4.9 x 3 14.7 Page 11 of 14 The Firs Primary School May 2015 To complete the sum in the same manner as the sum 49 x 3 would be completed with the decimal point placed 1 digit from the right hand side due the sum incorporating just 1 decimal number. Y6 ThHTU x U To reinforce long and short column multiplication methods to children. 4346 x 8 Children can approximate first 4346 x 8 is approximately 4346 x 10 = 43460 ThHTU 4346 x 8 32000 (4000 x 8) 2400 (300 x 8) 320 (40 x 8) 48 (6 x 8) 34768 ThHTU 234 4346 x 8 34768 Short column multiplication HTU x TU 372 x 24 Children will approximate first 372 x 24 is approximately 400 x 25 = 10000 HTU 2 372 x 24 1488 7440 8928 1 Page 12 of 14 The Firs Primary School May 2015 Any carry digits (overs) from partial products to be placed above sum under relevant place value therefore a space is needed if place value letters are noted. Carry digits from addition sums to be placed under the sum. (Stage 5) Using similar methods, they will be able to multiply decimals with up to two decimal places by a single digit number and then two digit numbers, approximating first. They should know that the decimal points line up under each other and is completed in accordance to previous examples’ layout. U. th hth x U 4.92 x 3 Children will approximate first 4.92 x 3 is approximately 5 x 3 = 15 U. t h 2 4.92 x 3__ 14.76 U. t h 2 This sum can be viewed and completed in the same way as 492 x 3 before adjusting the answer to suit place value. This is done by placing the decimal point 2 units from the left due to there being 2 decimal numbers in the question. Again, sum to be completed as 32 x 44 before making place value adjustments. 3.2 x 4.4 1.28 12.80 14.08 + - + - + - + - + - + - + By the end of year 6, children will have a range of calculation methods, mental and written. Selection will depend upon the numbers involved. Children should not be made to go onto the next stage if: 1) they are not ready. 2) they are not confident. Page 13 of 14 The Firs Primary School May 2015 Children should be encouraged to approximate their answers before calculating. Children should be encouraged to consider if a mental calculation would be appropriate before using written methods. Page 14 of 14