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Find a missing addend

A missing addend is the unknown part in an addition situation or equation, such as 7+=127+\square=12; the learner determines it by relating the known part to the total, often counting on or finding the difference, with sums within 20. Part–whole diagrams, ten-frames, and number lines can represent this relationship and establish addition and subtraction as inverse operations, without extending to larger numbers or symbolic generalizations.

Detailed Explanation: Find a missing addend

A missing addend is the number that makes the total.

Example:

7+=127+\square=12
  1. Start with the known number, 77.
  2. Count on until you reach (12)(12):
    (8,9,10,11,12)(8, 9, 10, 11, 12)
  3. You counted 55 numbers, so the missing addend is 55.
7+5=127+5=12

So, 5\boxed{5} is the missing addend.

Learn by doing: Find a missing addend

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Addition - Missing Value, Within 20


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