Why You Might Divide in Parts
Just as you sometimes decompose or break numbers apart to add,
subtract, or multiply, you might break numbers apart
to make division easier.
For example, to share 24 items into 4 groups, you could share the
first 12 items and then the other 12.
This is useful if you know 12 ÷ 4 but you do not know 24 ÷ 4.
How to Choose Parts
You should choose parts that you find easy to work with.
For example:
Decomposing numbers (breaking numbers apart) is a
very effective way to develop fluency with multiplication
and division. When dividing, you can break the dividend
into parts additively, but you cannot break the divisor into parts.
decomposition: the process of separating a number
into parts; for example,
12 = 10 + 2 or 20 = 4 × 5