When we write the number according to the place value of its digits, that form is the expanded form of a number.
Expanded form of 55561230 is:
50000000 + 5000000 + 500000 + 60000 + 1000 + 200 + 3 + 0
Expanded form of 555612300 i
500000000 + 50000000 + 5000000 + 600000 + 10000 + 2000 + 300 + 00 + 0