Compose+and+Decompose+Numbers


 * Compo sing/Decomposin g Numbers

It is important for students to develop the ability to compose and decompose numbers. For example, a student would be able to decompose the number 42 into the numbers 40 and 2. Conversely, the student would be able to compose the numbers 40 and 2 into the number 42. This skill helps students develop facility with multi-digit addition and subtraction.

** ** Example **

A student is asked to solve the problem 65+33 The student would decompose the numbers to create the following addition problems: 60+30 and 5+3. A student should be able to solve the new problems mentally and then compose the sums from each problem to create the answer to the original problem.

60+30=90 5+3=8 90+8=98

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References