Is 04 the same as 040?

No, 04 = 4 whereas 040 = 40. You usually do not put a zero before a non-zero number unless you are using a decimal point. If you meant to use a decimal point, then .04 and .040 are equal although the latter is considered to be more precise because it is accurate to 2 decimal places wheras the former is accurate to only one decimal place.