Compound Interest and the Rule of 72

Compound Intrest is when you gain intrest on the amount you have already gainned intrest on. If you have 50% a month intrest rate and u currently have $100 with regular intrest you gain $50 dollars every month. If you have compound intrest The 1st month you would gain 50% intrest on $100, so the next month you have $150 and instead of getting 50% intrest on the original you get 50% intrest on the new amount $150. The amount of intrest you get will go up. 1st month you gain $50 second $75.
Rule of 72 is a way of figuring out how long it will take for an investment gainning intrest to double. The formula is simply 72 divided by the intrest rate.