We made a decision when that game came out that we'd be keeping the combat calculator and equipment calculator as is. We started this website in 2004, we could have run RS classic features back then and that would have been the same as running 07 features now. It's time to move forward, not backwards.
Here's the old melee formula:

These symbols mean ⌊ ⌋floor which ultimately means to chop off anything after the decimal point. 3.0 becomes 3, 3.1 becomes 3, 3.999 becomes 3.
Graphic courtesy of the RS Wiki.