NumihanaCarrying is an exchange between place-value units. Ten ones have the same value as one ten. When an addition column makes ten or more, keep the remaining ones in that column and record the new unit in the next column. The small carrying row helps us remember it.
Work through the example
- Align 348 and 276. Estimate first: 350 + 280 is about 630.
- In ones, 8 + 6 = 14. Write 4 ones and record 1 ten above the tens column.
- In tens, 4 + 7 + the carried 1 = 12 tens. Write 2 tens and record 1 hundred above hundreds.
- In hundreds, 3 + 2 + the carried 1 = 6 hundreds. Read the answer as 624 and check 624 − 276 = 348.
Why it works
The small 1 above tens represents ten, while the small 1 above hundreds represents one hundred. The digit looks the same but its value changes with its column. No value disappears when we exchange; we record the amount in a different unit.
A common slip
A carry can be forgotten or counted twice. Before moving on, say the complete column sum, including any incoming carry. Once that column has been calculated, the carry has done its job.
For teachers & parents
Start with an example needing one carry before using this two-carry example. Ask the learner to explain why writing 14 inside the ones answer cell would spoil the alignment. Invite an alternative partitioning calculation as a check rather than treating one layout as the only valid strategy.
Talk it through
For 348 + 276, explain why the carried digit above tens is worth ten rather than one. Can you show the same exchange with a drawing?
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