- Darts (count down from 301/501)
- Blackjack (hand totals with aces)
- Poker (pot odds)
- Making Change
- Currency Exchange (learn currencies + convert)
- Time Zones (with DST / summer-winter)
- Doomsday Algorithm (weekday from date)
- Bowling (frame scoring with strikes/spares)
- Snooker (break scoring: red-color sequences)
- Yahtzee (sum combinations, remaining needed)
- F1 points (race position → points)
- Football league tables (points from W/D/L)
- Cricket scoring
- Mental squaring
- Divisibility tricks
- Percentage shortcuts
- Inventory/stock counting
- Distance between cities
- Speed/distance/time problems
- Fermi problems (order of magnitude estimates)
- Recipe scaling (fractions)
- Bartending (cocktail ratios)
- Discounts / sale prices
- Tipping