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Grade 1 · Maths · Lessons
Adding to a hundred
🔟tens1️⃣ones➕add💯a hundred
Adding bigger numbers.
The big ideaTens go with tens, ones go with ones. Ten ones make a new ten.

How it works

Add tens to tens. Add ones to ones.

If the ones make ten or more, they make a new ten.

Add the new ten to the tens.

39+2=41ten ones made a new ten
39 and 2: nine ones and two ones make 11, so a new ten (gold) is made.

Example 1: Add a ten

  1. ? = 35 + 10
  2. The ones stay the same.
  3. Only the tens change.
  4. So the answer is 45.

Example 2: Ones make a new ten

  1. ? = 39 + 2
  2. Ones first: add the ones.
  3. If they make ten or more, move a ten over.
  4. So the answer is 41.

Example 3: Add ten to a number

  1. 17 + 10 = ?
  2. Look at the tens digit.
  3. It goes up by one. The ones stay.
  4. So the answer is 27.

Words to know

tens
Groups of ten.
ones
The single ones left over.

Watch out

Try it

  1. ? = 52 + 9
  2. 31 + 4 = ?
  3. 10 + 57 = ?
Answers: 1. 61 · 2. 35 · 3. 67
For grown-upsUse ten sticks and loose ones. Add some, and swap ten loose ones for a new stick.
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