The mod maths took a while to get 1. Divide the number by the MOD 2. Round DOWN to a whole integer 3.Take the integer from step#2 multiply by MOD 4. Take the DIFFERENCE between the ORIGINAL VALUE AND STEP# 3 This becomes your NEW value.
its a good video, but way too complicated. i think it is becuase my middle school mind cant process all of this great explanation though i just didnt get the terms and stuff :(