Definition
Decompose a number
To decompose a number is to split it into parts that still make the same whole.
What it means
Start with the whole and take it apart into useful value-parts. The number has not changed: putting the parts back together must make the original whole. You can choose different parts for different calculations.
Remember it
Decompose opens the whole into parts without changing its value.
Example
Decompose 74 into tens and ones: 74 = 70 + 4. Another valid decomposition is 74 = 50 + 24, because both parts still add to 74.
Watch for
Changing 74 to 70 is not a complete decomposition because 4 has been lost. All the parts together must still total 74.
Common mix-up
Decompose splits the whole into parts. Compose uses parts to build the whole.
Exact meaning
To decompose a number is to express it as two or more parts whose combined value equals the original number. A number can have many valid decompositions, and the total value must be preserved.