The addition formula can be tested by subtraction. Take the formula in the following figure as an example, and do vertical calculation first.

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Addition is tested by subtraction. Add and subtract one of the addends to see if it is equal to the other.

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Subtraction is checked by addition, and written vertically first.

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Check the difference and subtract it to see if it is equal to the minuend.

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To sum up, addition is checked by subtraction, and subtraction is checked by addition. It is more helpful to form a good habit of checking the calculation.

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Pay more attention to oral arithmetic practice at ordinary times, not only to improve the accuracy, but also to speed up oral arithmetic.

Matters needing attention

In the usual calculation, paying attention to checking calculation can increase the accuracy of the problem.