Column subtraction

For grown-ups: this lesson in words

Years 3 to 6 · Maths

Column subtraction: I can subtract in columns, exchange when the top digit is too small, and add to check.

1. Here is 352 as base 10 blocks: 3 hundreds, 5 tens and 2 ones.

   352 − 121. Columns let us take away the ones, the tens and the hundreds one at a time.

   Picture: Base 10 blocks showing 352: 3 hundreds, 5 tens and 2 ones.

2. 352 − 121. Line up the digits: ones under ones, tens under tens, hundreds under hundreds.

   Start on the right. Ones: 2 − 1 = 1.

   Tens: 5 − 2 = 3.

   Hundreds: 3 − 1 = 2. So 352 − 121 = 231.

   Picture: 352 take away 121 worked out as a column subtraction: the answer is 231.

3. Your turn: Take away the ones, then the tens, then the hundreds. What is 586 − 342?

   Picture: 586 take away 342 set out as a column subtraction, with an empty answer row.

   Type a number.

   Answer

   The answer: 244

   244. Ones: 6 − 2 = 4. Tens: 8 − 4 = 4. Hundreds: 5 − 3 = 2.

   Picture: 586 take away 342 worked out as a column subtraction: the answer is 244.

Words to know

column:

Digits that line up one above the other: ones, tens, hundreds.

exchange:

Exchange, or borrow: swap 1 ten for 10 ones when the top digit is too small.

difference:

The answer to a subtraction.

inverse:

The opposite. Addition undoes subtraction.