How_To_Be_Good_At_Math

CALCULATING • COLUMN SUBTRACTION 97

Now we can subtract 6 tens from

12 tens. The answer is 6 tens.

Write the 6 in the tens column.

Now we can subtract 7 ones from

12 ones instead. The answer is 5

ones. Write the 5 in the ones column.

932 − 767 = 165

Next, we subtract the tens.

We can't subtract 6 tens from

2 tens so we need to exchange one

of the hundreds for 10 tens. Write a

1 next to the 2 in the tens column to

show that we now have 12 tens.

Change the 9 in the hundreds

column into an 8 to show that we

have just exchanged one of the

hundreds for 10 tens.

Now we can

subtract 7 ones

from 12 ones

Change this

from 9 hundreds to

8 hundreds because

we exchanged one

of the hundreds for

10 tens

−

H T O

932

Now we can

subtract 6 tens

from 12 tens

−

−

H T O

H T O

767

932

932

5

5

5

Finally, we need to subtract

7 hundreds from 8 hundreds,

leaving 1 hundred. Write the 1 in the

hundreds column.

So, 932 – 767 = 165

−

H T O

932

−

H T O

767

165

65

(^21)
We can't subtract
6 tens from 2 tens, so
we need to exchange
one of the hundreds
for 10 tens
1
(^8121)
8 12
932
8 12
Now we can
subtract 7 hundreds
from 8 hundreds
767
12
767
767
When we need to subtract a larger
amount from a smaller amount,
we exchange 1 ten, hundred, or
thousand from the column to the left.
096_097_Column_subtraction.indd 97 29/02/2016 14:10