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Check subtraction with addition informally

Subtraction can be checked by adding the amount taken away to the difference: if a quantity is reduced from a total, the difference plus the amount removed should recreate the original total. For numbers within 20, this relationship may be represented with drawings, number paths, or related equations, supporting recognition that addition and subtraction are inverse operations and helping identify an incorrect difference; formal algebraic generalizations and larger-number methods are beyond this scope.

Detailed Explanation: Check subtraction with addition informally

When you subtract, you take away. You can check your answer by adding back the amount you took away.

Example:

14−6=814-6=8
  1. Start with the difference: 88.
  2. Add the amount taken away: 66.
8+6=148+6=14
  1. The answer is 1414, which is the starting number. So, 88 is the correct difference.

Subtraction and addition are related:

14−6=8and8+6=1414-6=8 \quad \text{and} \quad 8+6=14

If the addition does not give back the starting number, check your subtraction.

Learn by doing: Check subtraction with addition informally

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Subtraction - Missing Value, 1 Digit, 1 Number


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