The rule of 72
Lesson 5 of 13 in our free Build Wealth the Boring Way guide: a 5-minute money game with the key points below.
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Questions you'll answer
Savings grow at 3% a year. Using the rule of 72, roughly how long until they double?
If prices rise at 3.1% a year (the latest CPI figure in our 2026/27 pack) and keep going, roughly how many years until prices double?
A card balance is left untouched at 24% APR. Roughly how long until the debt doubles?