Post on 13-Apr-2017
transcript
Multiplication and Division
‘English is everywhere, Maths is massive’
Created by Richard Bull
First things first:
You need to learn your tables!
Every multiplication problem can be broken down into simple tables calculations.
When you are asked to find the “product” of some numbers, that means multiply them.
Created by Richard Bull
Do you know these?
Traditional method 21 x 13 = ?
2 1
x 1 33 x 1 = 3 write down the 3.
36 3 x 2 = 6 write down the 6
10 x 1 = 10 write down the 101 x 2 = 2 write down the 2
Add the numbers
1 02
2 7 3
Traditional method 45 x 34 = ?
4 5
x 3 44 x 5 = 20 write down the 0, carry the 2.
08 4 x 4 = 16, add 2 write down the 18
30 x 5 = 150 write down the 50, carry the one
3 x 4 =12, add the 1, write down the 13
Add the numbers
5 03
5 3 3
1
1
1
1
2
Grid Method – part 1255 x 5 = ?
First split the number into hundreds, tens and units.
255 splits into 200, 50, 5
Then, multiply each of the numbers by 5.200 x 5 = 100050 x 5 = 2505 x 5 = 25
This can be placed in a grid
Grid Method – part 2255 x 5 = ?
x200 50 5
200 x 5 50 x 5 5 x 5
5
Finally, add the three numbers together to get your answer.
1000 + 250 + 25 = 1275
So 255 x 5 = 1 275
1000 25250
First, split the numbers up. 255 splits into 200, 50 and 5. These go
along the top of the grid.25 splits into 20 and 5. These go down
the sides.
Grid Method – part 1255 x 25 = 6375
Put the numbers on the grid
x 200 50 5
20
5 Add up each column, then add the resulting numbers together.
Grid Method – part 2255 x 25 = 6375
4000
25010001001000
25
4000 + 1000 + 100 = 51001000 + 250 + 25 = 1275
6375
2 5
510 5
22 x 5 =
10
5 x 5 = 25
Lattice method – part 125 x 5 = ?
1. Make the lattice (grid) as shown
2. Multiply each number above a column by the numbers in every row3. Write the answers in the lattice. Making sure you have only 1 digit in each triangle
2 5
510
51
52
2
Add along the diagonal2 + 0 = 2
Lattice method – part 2 25 x 5 = ?
3 6
82
4 84
3 x 8 =24
6 x 8 = 48
Lattice method – part 136 x 8 = ?
1. Make the lattice (grid) as shown
2. Multiply each number above a column by the numbers in every row
3. Write the answers in the lattice. Making sure you have only 1 digit in each triangle
3 6
82
4
82
84
8
Add along the diagonal line4 + 4 = 8
Lattice method – part 2 36 x 8 = ?
3 6
1
3
3 6
1 x 3 = 3
1 x 6 = 6
Lattice method – part 136 x 13 = ?
1. Make the lattice (grid) as shown
2. Multiply each number above a column by the numbers in every row
3. Write the answers in the lattice. Making sure you have only 1 digit in each triangle
9 81
3 x 6 = 18
3 x 3 = 9
3 6
1
3
3 6
Lattice method – part 236 x 13 = ?
9 8
4 6 8
1
Add along the diagonal line
6 + 1 + 9 = 16
1
Which of these did you use to calculate 21 × 32?
20 1
30
2
600 30
40 2
Are there any other methods?
32× 21
32+ 640
Answer: 672Answer: 672
2 1
3
2
06
03
04
02
27
6
0
Answer: 672
Choose a method to calculate 43 × 17?
40 3
10
7
400 30
280 21
Are there any other methods?
43× 17301
+ 430Answer: 731Answer: 731
4 3
1
7
04
03
28
21
13
7
0
Answer: 731
1
Multiply these using whichever method you like (no calculators!):
1. 26 × 14
2. 74 × 39
3. 124 × 16
4. 249 × 179
= 364
= 2886
= 1984
= 44571
Division
Learning objective:Can I divide numbers without using a
calculator?Grade C
Draw the bus stop:
Divide each value by 3, not forgetting to carry any
remainders.The answer is on top!
Answer: 45
03
Calculate 135 ÷ 3
Bus Stop MultiplesWe need to do the following
calculations:10 × 3 = 3010 × 3 = 3010 × 3 = 3010 × 3 = 305 × 3 = 15
How many 3s in total?Answer: 45
1 3 54 5
1 1 Total so far: 30
Total so far: 60
Total so far: 90
Total so far: 120
Total so far: 135
Divisor
Draw the bus stop:
Divide each value by 14, not forgetting to carry any
remainders.The answer is on top!
Answer: 23
014
What about 322 ÷ 14
Bus Stop MultiplesWe need to do the following
calculations:10 × 14 = 14010 × 14 = 140
3 × 14 = 42
How many 14s in total?Answer: 23
3 2 22 3
3 4 Total so far: 140
Total so far: 280
Divisor
Total so far: 322
Calculate these, without a calculator!
1. 168 ÷ 7
2. 222 ÷ 6
3. 384 ÷ 12
4. 952 ÷ 17
= 24
= 37
= 32
= 56
Created by Richard Bull