why is 15 wrong when the answer is 15.0

Question

I understand floats but 4.0 + 3 = 7 or 7.0...same thing!

Answer 1

7 equals 7.0. That is true.
But if the question is what the output will be, then you have to be precise, and pay attention to the data types.

Answer 2

In science the answer to 4.0 + 3 would be 7 because you need to pay attention to the significant digits. But in coding it is all about data types.

Answer 3

ok thank you