Do you know about

THE RULE OF 72?

Here is THE RULE OF 72:

If your fiat is losing value at 7% annually, that means in 10 years you’ll lose more than half of its purchasing power.

72 / 7 =10.286

This is a shorthand equation for calculating the half-life of decline.

The full equation is:

V= P x (1- r) ^t

Ending value = principal times one minus rate to the power of time

This is a formula for calculating the decline in value over time with r being the percentage rate.

Note that this is almost the same equation for calculating compound annual growth ( 1+ r) instead of (1-r).