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Grade 1 · Maths · Lessons
The missing part
🧩part🍬whole❓missing➖take away
The missing part.
The big ideaA whole is two parts. Find the part that is missing.

How it works

A whole is made of two parts.

If you know the whole and one part, take the part away to find the other.

Check by adding the two parts.

Whole: 9• part: 7• part: ?Find the part• 9 − 7 = 2• check: 7 + 2 = 9
9 is the whole: 7 and 2.

Example 1: Take away a part

  1. 9 − 7 = ?
  2. The whole is 9. One part is 7.
  3. Take the part away from the whole.
  4. So the answer is 2.

Example 2: The same, written the other way

  1. ? = 9 − 7
  2. The question is written backwards.
  3. It means the same: find the missing part.
  4. So the answer is 2.

Example 3: The part is in the middle

  1. 8 = 11 − ?
  2. The whole is 11. One part is missing.
  3. Take away what you know.
  4. So the answer is 3.

Words to know

whole
All of something.
part
A piece of the whole.

Watch out

Try it

  1. ? = 12 − 3
  2. ? = 9 − 4
  3. 12 = 4 + ?
Answers: 1. 9 · 2. 5 · 3. 8
For grown-upsHide some counters under a cup and ask how many are hidden.
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