In one of Gregmat’s videos and for the following equation: 15.99999996/4.0002 he simplified the equation as such for 15.99999996 = 16-(4X10^-8).

Why is this so? why is it 4X10^-8?

Hint: a^2 - b^2 = (a + b)(a - b)

That part I got, but my question is , and maybe its a simple one, but how was it 4\times10^{-8}? why the 4 and not 16-6\times10^{-8}?

Because 16-6\times10^{-8} = 15.99999994.

true true okay thanks!

I was calculating is as 0.00000006 rather than the 0.99999994