How to use it
- Find 10% by moving the decimal one place.
- Half of 10% gives 5%.
- Combine for 15%, 20%, 25%, etc.
See it in action
$46 bill: 20%≈$9.20; 15%≈$6.90.
How to verify it
A 20% tip should be about one-fifth of the bill.
Estimate Tips Quickly
Use 10% as an anchor and combine it to get common tip rates.