Composing and Decomposing Numbers

 

349

is made up of
hundreds tens units

3

4

9

Composing

So 349 is composed of 3 hundreds, 4 tens and 9 units, in other words:

300 + 40 + 9 ⇒ 349
"Composing"

 

Example: Compose 2 hundreds, 7 tens and 9 units.

200 + 70 + 9 = 279

Decomposing

Decomposing is when you break the number apart

349 ⇒ 300 + 40 + 9
"Decomposing"

 

Example: Decompose 3,456

3,456 = 3,000 + 400 + 50 + 6

Standard and Expanded Form

Some people call the two different forms "Standard" and "Expanded":

349 300 + 40 + 9
Standard Form Expanded Form

 

Example: Put 925 into Expanded Form

925 = 900 + 20 + 5

Decimal Numbers

You can also compose and decompose decimal numbers:

37.2 ⇒ 30 + 7 + 0.2
"Decomposing"

 

4 + 0.7 + 0.08 ⇒ 4.78
"Composing"

 

Example: Decompose 1.35

1.35 = 1 + 0.3 + 0.05