Addition learning path

Number Splitting: Break Addition into Easy Parts

A number is made of parts. Splitting addends into tens and ones lets you handle one simple sum at a time, without needing to hold the full calculation in working memory.

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The strategy

How it works

Split each addend into tens and ones.
Add the tens together and the ones together.
Combine both totals, regrouping the ones if needed.

See it in action

Worked examples

Example 146 + 31

Split: 40 + 6 and 30 + 1.
Tens: 40 + 30 = 70; ones: 6 + 1 = 7.
70 + 7 = 77.

Answer: 77

Example 238 + 27

Tens: 30 + 20 = 50; ones: 8 + 7 = 15.
Combine 50 + 15.
50 + 15 = 65.

Answer: 65

A quick heads-up

Common mistakes to avoid

Treating 15 ones as 15 tens; keep the place value clear when regrouping.
Combining only one pair of parts; check that both the tens sum and ones sum are included.

Your turn

Check your understanding

Choose an answer to see instant feedback and a short explanation. You can take the quiz again any time.

Question 1 of 3

What is 52 + 26?

Keep the momentum

Try a few practice problems

Choose a comfortable range and work through a short round with the free mental math trainer.

Practice addition