> I still do not understand the formula.
> I need 400/6.98 = 57, not 57.31.

[400/6.98] = 57, not 57.31.

The brackets are not just a variation on parentheses. They denote the whole part function.

> I have to round down the answer
> via using a formula or the program
> will pick up the true value

It depends on what program or what language you use.

The whole part function is also called floor. Check your manuals. In C or C++ or Java you could just make a recasting to an integer:

int N = (int)(400/4.68);