## Build Calculation Speed Practicing the 10 Pair Complements

The main method of addition and subtraction on the abacus is understanding and using the 5 complement pairs of 10, i.e.

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# Tag: complement addition

## Build Calculation Speed Practicing the 10 Pair Complements

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The main method of addition and subtraction on the abacus is understanding and using the 5 complement pairs of 10, i.e.

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