Multiplication of Cassette Ratios The title can not explain it more specifically, however, recently I watched a video where I guy explains a calculation and tells the result gives how easily you climb ramps. Here is the calculation:

Rear cassette: Biggest sprocket size / smallest sprocket size
Crank cassette: Biggest sprocket size / smallest sprocket size

You multiply the end results and multiply it again with 100 which gives you a percentage. 

Here is an example:

Say I have a front cassette 22-32-44 and a rear cassette 11-36. The calculation is as follows: 

(44/22)*(36/11)*100 = %654

So the guy says the bigger this number, the easier you climb ramps? That doesn't make ay sense to me. Does it hold any truth or does he try to mean something else?
As others have already noted, the figure to which you refer pertains to the drivetrain's range, not to the lowest gear. The mechanical advantage that allows you to climb hills easily (small chainring driving your largest cassette's sprocket, say 22x36 in your example) is customarily expressed in gear-inches, a rather meaningless measure -- it indicates the equivalent diameter of a wheel that would be geared 1/1, but a standard nonetheless. 16 gear-inches would be considered small. Your example yields 15.9 gear-inches.

An excellent gear calculator can be found here. Play with it and all should become clear.