Writing numbers in their expanded forms basically requires dividing the number into parts of units, tens, hundreds, ten hundreds and so on and so forth but such that they when added they give the original number. In the case above the expanded form of 157,488 will be as follows:

157,488

100,000+50,000+7,000+400+80+8

Adding all these numbers would give the original number.

157,488

100,000+50,000+7,000+400+80+8

Adding all these numbers would give the original number.