A missing addend is the unknown part in a whole-number addition relationship, such as ; the learner determines it by identifying the difference between the known addend and the total, using subtraction, counting on, or a part–part–whole model. This connects addition and subtraction as inverse operations and supports reasoning about place value and later unknowns in equations; the scope is whole-number situations with totals within 100, not fractions, negative numbers, or generalized algebraic equations.
A missing addend is the number that is needed to complete an addition problem.
Example:
Think: “What number can I add to to make ?”
Use subtraction to find the missing part:
So, the missing addend is .
Check your answer by adding:
Therefore,
The missing addend is . Subtraction helps because it finds the difference between the total and the known addend.
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