A number multiplied by a power of 10 makes the decimal point move to the right as many as there is zeroes in the power of 10: for example, 1*10=10, 5.5*100 = 550.
In your case:
a) 4301 = 430.1 * 10 = 43.01 * 100 = 4.301 * 1000... more the decimal point goes backward, the more zeroes you add to the power of 10.
b) 687 = 68.7 * 10 = 0.687 * 1000 = 0.0687 * 10 000, if the decimal point goes beyond the last number, you add zeroes to the left before the decimal point.
c) Same thing here! 56 = 5.6 * 10 = 0.56 * 100, etc..
Hope this helps! ;)
