methods of multiplication
DESCRIPTION
Methods of Multiplication. Heatherside Junior School. Multiplication. x x x x x x x x x x x x x x x. x x x x x x x x. x x x x x x x. 2 x x x x x x x. 2 x x x x x x x. lots of . times. groups of. repeated addition. array. product of. multiply. multiple of. - PowerPoint PPT PresentationTRANSCRIPT
Multiplication
lots of times groups of
repeated addition array
multiple of multiplyproduct of
doublex x x x x x x x x x x x x x x x
xxxxxxx
xxxxxxxx
x x x x x x x x x x x x x x x
Step 1 – Multiplication as arrays
2 x 3 = 6
2 + 2 + 2 = 6
3 x 2 = 63 + 3 = 6Understanding that
multiplication is repeated addition
Recognising that 3x2 gives the same answer as
2x3
x 2 3 4 5 6 7 8 9
2 4
3 6 9
4 8 12 16
5 10 15 20 25
6 12 18 24 30 36
7 14 21 28 35 42 49
8 16 24 32 40 48 56 64
9 18 27 36 45 54 63 72 81
Stage 1: counting in 10s, 5s, and 2s Stage 2 (by the end of Year 2): x10, x5, x2 Stage 3 (by the end of Year 3): x3, x4, x9 Stage 4 (by the end of Year 4): x6, x7, x8
Step 2 – Knowing tables facts is key‘Learn Its’ – a progressive approach 3 facts
5 minutes3 weeks
‘Learn Its’ vocabulary
FACTS SWITCHERS FACT FAMILIES3 X 3 = 9 4 X 3 = 125 X 3 = 15
3 X 4 = 123 X 5 = 15
9 ÷ 3 = 312 ÷ 3 = 415 ÷ 3 = 5
Step 3 - Partitioning
This method helps show the value of each digit in a
number. Children develop a greater understanding of the
reasonableness of an answer and they are able to
apply known facts.
23 x 8 =
20 3
Step 4 - The Grid Method
X 20 3
8 160 24
• The number is partitioned and placed on the grid.• The total is added to calculate the final answer.
160 + 24 = 184
23 x 8 =
Step 5The Expanded Column Method
The question is…
38 x 7 =
The number is partitioned…
38 x 730 8 x 7
30 + 8 x 7 56 (7 x 8) + 210 (7 x 30) 266
Step 6 ….This is then reduced to Short Multiplication
38 x 7 =
38 x 7 = 266
We aim for children to begin to be able to use short multiplication for TU x U
by the end of Year 4.
The short method
38 x 7 266 5
Using the Grid Method for TU x TU
Remember to partition the
numbers using known facts first.
X 60 3
40 2400 120
2 120 6
63 x 42 =
2400 + 120 = 2520
120 + 6 = 126
2520 + 126 = 2646
Moving from the Grid to Column Method for TU x TU
The question is
56 x 27 =
56 x 27 42 (7x6) 350 (7x50) 120 (20x6)+ 1000 (20x50) 1512 1
The Grid Method for larger numbers
X 80 9100203
89 x 123First partition each number 89 x 123[80 9] [100 20
3]This is then shown on a grid like this…
Multiplying using the grid method
X 80 9100
20
3
Firstly, multiply each column and row and record the answer in the correct box
8000
1600
240
900
180
27
X 80 9
100 8000 900
20 1600 180
3 240 27
Completing the calculationNow total up all the yellow numbers.
= 8900
= 1780
= 267
Add all the totals to get the final answer
= 10,947