How To Write In Expanded Form Using Components?

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.

100,000.500,000.400.80.8

When writing a number in expanded form using exponents, you have to write the number like this: (1x10 to the power of 5)+(5x10 to the power of 4)+((7x10 to the power of 3)+(4x10 to the power of 2)+(8x10 to the power of 1)+(8x1)
I have a question for you, too.
Children learn this kind of stuff in 6th grade. Why is she learning it in 5th?

Six hundred millions, two hundred thousands, one thousand, nine tens, four ones