Declaring variables a lengthy way..?

I keep asking myself lately and its bugging me, out of curiosity why do people declare variables like this…

int level_width = current_level / 4 * 384 + 640;

When it could be:

int level_width = current_level / 2176;

?

Is it to save using a calculator? Sorry if it sounds stupid, I have been pretty anxious to ask on here…