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Making 100 to add and subtract worksheets

37 + 48 + 63 looks like three numbers to add, but 37 and 63 make exactly 100. These free printable worksheets practise finding that pair first — in three-number sums, and in taking two numbers away at once — for grades 3 and 4.

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Making 100 to add and subtract
Making 100 to add and subtract worksheet — Pairs that make 100, free printable with answer key

The answer key prints on a separate page.

What's on this sheet

Addition can be done in any order, and that is the whole strategy. 37 + 48 + 63 becomes (37 + 63) + 48, which is 100 + 48 = 148. The middle number never pairs with either end, so the only round pair on the line is the one the child is meant to find.

Why this sheet works

Subtraction has the same move in reverse. Taking away 47 and then 53 is the same as taking away 47 + 53 = 100 at once, so 391 − 47 − 53 becomes 391 − 100 = 291. Children often find this surprising, and it is worth checking one the long way so they believe it.

How this one works

69 + 57 + 31

69 + 57 + 31=(69 + 31) + 57
(69 + 31) + 57=100 + 57
100 + 57=157
  1. Two of these make 100, so add that pair first.
  2. Work out the easy part first: (69 + 31) + 57 = 100 + 57.
  3. Then finish: 100 + 57 = 157.

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