How_To_Be_Good_At_Math

CALCULATING • LONG MULTIPLICATION 121

Now multiply 6 ones by 4 tens.

The answer is 24 tens. Write the 4

in the tens column and carry the 2 into

the hundreds column to add on at the

next stage.

Next, multiply 8 tens by 4 tens.

The answer is 32 hundreds.

Add the 2 hundreds that we carried

over to make 34 hundreds. Write the

4 in the hundreds column and the

3 in the thousands column.

Now we have multiplied all

the digits on the top row by all

the digits on the bottom row, we add the

two lines on our answer together:

258 + 3440 = 3698

So, 86 × 43 = 3698

Now we’re going to multiply all the

digits on the top row by 4 tens and

write the answers on a new line.

When we multiply by this 4, we’re

actually multiplying by 40, which is 10

times 4. So, first we put a 0 in the ones

column on a new line as a place holder.

86

43

258

86

86

86

86

258

258

258

258

3698

43

43

43

43

0

40

3440

3440

2 carried into the

hundreds column

Put a 0 on a

new line in the

ones column

Multiply

6 ones

by 4 tens

Multiply 8 tens

and 6 ones

by 4 tens

The 2 hundreds

carried over is added

to the number put

in this column

1

×

×

×

×

×

Th H T O

Th H T O

Th H T O

Th H T O

Th H T O

1

1

1

1

2

2

2

The final stage of our

calculation involves

column addition.

We looked at this

on pages 86-87.

86 × 43 = 3698

Add the two lines in +

the answer together

This 4 means

4 tens or 40

Multiply 8 tens

by 4 tens

120_121_Long_multiplication.indd 121 29/02/2016 14:11