Big Trouble with formulas

I`m having a big issue,

I finished R6 of quant and Im in the last LOS of R7, but Im having such a big trouble to remember formulas, it`s so use to confuse some of them, does anyone have a tip for me?

What is the formula that you’re trying to remember?

Like MAD, Variance, Chebyshev`s, the ones from quantiles (Ly, Py) the percentiles as ex…

Im also seeing a lot of end of chapter question on R7 that theyre just too big and time consuming, for example he give me 10 observations without giving me the mean and ask the MAD.

See question 22 from page 445 as an example, in this chapter there are too many formulas that is hard to remember (unlike TVM from R6 that you can do by intuition with a financial calculator),

I need some help!