Scientific Notation is a number between one and ten times ten to the power of a number. I'll go through the steps below.
1: get a decimal from 130400000 but count the number of times that you move the decimal.
0 - 130400000.
1 - 13040000.0
2 - 1304000.00
3 - 130400.000
4 - 13040.0000
5 - 1304.00000
6 - 130.400000
7 - 13.0400000
8 - 1.30400000
2: So you need to move the decimal 8 times to the left, and you get 1.304! scientific notation is just moving a decimal... sooo...
1.304 X10^8
That is the answer. X10 is used with every scientific notation problem, and 8 is the number of times you'll have to move the exponent to get 130,400,000