The first number to the right of the decimal has the most value and the second has more value than the third, etc., so you compare them one at a time starting at the first digit. when you get to one that is not identical, the bigger one indicates the bigger number, no matter what follows.
1) They both are the same whole number (4) so we go on to the decimals.
2) They both have the same first decimal (tenths place) of 0, so on to the next.
3) The second decimal digits (hundredths place) are not identical. Since the first number has a larger value (5) than the second number (0), the first number is bigger. It does not matter what follows.