The Rule of 72 tells you either

1) how long it takes for your money to double at a given interest rate

2) how long it takes for prices to double at a given inflation rate

This is done by dividing the rate into 72. e.g.

at 03% interest/ inflation, your money / prices will double every 72/3 = 24 years

at 06% interest/ inflation, your money / prices will double every 75/6 = 12 years

at 12% interest/ inflation, your money / prices will double every 76/12 = 6 years