MULTIPLICATION Multiplication and Division should be taught alongside the learning of formal times tables PHASE ONE: PRACTICAL METHODS - DOUBLING Strategies and methods: Recording: Teacher to model verbally: “Double three is six” Practical work using a variety of objects and 2 of 3 is 6 Lay out a small amount of numbers Teacher to model recording both in columns and Count them horizontally Double using a mirror or more counters Put them together and count the total Extend by moving into doubling mentally 3 2 6 x MULTIPLICATION PHASE TWO: PRACTICAL METHODS – COUNTING IN TWOS, FIVES AND TENS Strategies and methods: Recording: Emphasise the links to repeated addition, Teacher models the calculations as follows: groupings and the commutative nature of multiplication (i.e. 3 x 2 = 2 x 3) Create several pairs and count them: Create groups of five and count them: Create groups of ten and count them: 1 1 3 3 x 2 6 5 x 2 0 0 x 3 0 MULTIPLICATION PHASE THREE: REPEATED ADDITION USING AN ARRAY / EQUIPMENT Strategies and methods: Recording: Children to start recording their calculation in Move on to developing the children’s columns understanding of arrays Solve one-step problems involving multiplication, by calculating the answer using concrete objects, pictorial representations and arrays with the support of the teacher. Make connections between arrays, number patterns, and counting in twos, fives and tens. 2 5 4 0 x MULTIPLICATION PHASE FOUR: REPEATED ADDITION ON A NUMBER LINE Strategies and methods: Recording: 1 2 Extension: Start from numbers other than zero. Sums recorded in the same way 3 1 2 6 2 4 6 4 5 7 4 2 6 2 x x x x MULTIPLICATION PHASE FIVE: GRID METHOD – UP TO HUNDREDS, TENS AND ONES BY ONES Strategies and methods: Recording: EXAMPLE 1 The children use their knowledge of 23 x 4 = ? partitioning to understand the larger number This is then partitioned into its constituent tens and ones The multiplier is placed to the bottom left of the grid, and first the ones, then the tens are calculated by multiplying by the multiplier. The answer to each part of the calculation is written into the corresponding box on the grid The ‘part’ answers are added together to give the final total 80 x 4 20 3 80 12 80 + 12 = 92 23 x 4 = 92 12 92 + 23 x 4 92 EXAMPLE 2 123 x 7 = ? x 100 20 3 7 700 140 21 700 + 140 + 21 = 861 123 x 7 = 861 700 + 123 140 x + 7 21 861 861 MULTIPLICATION PHASE SIX: GRID METHOD – HUNDREDS, TENS AND ONES BY TENS AND ONES Strategies and methods: Recording: EXAMPLE 1 The children use their knowledge of 34 x 25 = ? partitioning to understand the larger number This is then partitioned into its constituent hundreds, tens and ones The multiplier is also partitioned into its constituent parts. The multiplier is placed to the bottom left of the grid, with the tens in a row above the ones First the ones, then the tens are calculated by multiplying by the ones multiplier. The answer to each part of the sum is written into the corresponding box on the grid Next the ones, then the tens are calculated by multiplying by the tens multiplier. The answer to each part of the calculation is written into the corresponding box on the 750 + 100 = 850 grid 34 x 25 = 850 The ‘part’ answers are added together to EXAMPLE 2 give the final total 351 x 43 = ? Check with estimation x 30 4 20 600 80 5 150 20 x 300 50 1 40 12000 2000 40 3 900 150 3 21000 + 2150 + 43 = 861 123 x 7 = 861 MULTIPLICATION PHASE SEVEN: FORMAL METHOD – UP TO HUNDREDS, TENS AND ONES BY ONES (SHORT MULTIPLICATION) Strategies and methods: Recording: EXAMPLE 1 The children again use their knowledge of 24 x 3 = ? partitioning here, but do not write the number into its constituent parts, but leave it as a whole number, with each digit sitting in the correct column The children start with the ones, and record the answer to this part of the calculation with the one in the ones column, and the ten value carried into the tens column The children then multiply the tens by the multiplier. Any carried tens are added to this, and the answer is record in the tens column. 2 4 3 7 x 2 1 EXAMPLE 2 351 x 4 = ? 3 5 1 4 1 4 0 4 2 x MULTIPLICATION PHASE EIGHT: FORMAL METHOD (LONG MULTIPLICATION) Strategies and methods: Recording: This expands on the short multiplication method of Phase Six The children use their knowledge of place value to make sure that digits of corresponding value are in the correct column When multiplying by the tens multiplier, a 0 is automatically placed in the ones column for that row. The children use their knowledge of tables to work out the answers, then restate them with the correct values: “Seven multiplied by three is twenty one, so seven multiplied by thirty is two hundred and ten”. In the example given, the 2 2 tens multiplier is calculated first When multiplying by the ones multiplier, there is no place holder needed. Children must remember to record any carried numbers, and include them in the 3 final total for the calculation 2 8 3 8 6 1 1 1 4 9 7 5 2 7 x 4 0 8 8 MULTIPLICATION PHASE NINE: SHORT AND LONG MULTIPLICATION USING DECIMALS Strategies and methods: Recording: This expands on the short multiplication method of Phase Eight Children need to be reminded that the ones need to line up in the ones column The decimal points need to line up as part of the column method Use the short multiplication method to multiply numbers up to two decimal places by a single-digit number 2 3 6 .1 5 x .4 5 1 Use the long multiplication method to multiply numbers up to two decimal places by a two-digit number The decimal points need to line up as part of the column method As with long multiplication in Phase Eight, start with the larger multiplier – use place holder zeros to support column methods 3 .1 6 x 2 4 6 3 .2 0 1 1 2 .6 4 2 7 5 .8 4