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Use addition fact families

An addition fact family connects two addends and their sum through related equations: the two orders of addition and the two corresponding subtraction facts, such as 6 + 4 = 10, 4 + 6 = 10, 10 − 6 = 4, and 10 − 4 = 6. This establishes addition and subtraction as inverse operations and links part–part–whole relationships, limited to whole-number facts with sums through 20 rather than larger numbers or generalized algebraic fact families.

Detailed Explanation: Use addition fact families

A fact family uses the same three numbers to make two addition facts and two subtraction facts.

Use the numbers 77, 55, and 1212.

  1. The two smaller numbers are the parts: 77 and 55. The largest number is the whole: 1212.
  2. Add the parts in both orders:
    • 7+5=127+5=12
    • 5+7=125+7=12
  3. Start with the whole, 1212, and subtract one part at a time:
    • 12−7=512-7=5
    • 12−5=712-5=7

So, the fact family is:

7+5=127+5=12 5+7=125+7=12 12−7=512-7=5 12−5=712-5=7

The addition facts put the parts together. The subtraction facts take one part away from the whole.

Learn by doing: Use addition fact families

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    Fact Family - Addition - Triangle to Fact

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