How to play

Tap a poker card, then an operator or parenthesis, to build an expression. Use all four cards exactly once and make 24. Aces count as 1, while Jacks, Queens, and Kings count as 11, 12, and 13. Calculations use exact fractions.

Choose a comfortable pace

• Untimed: no clock; useful when learning or when fatigue varies.
• Relaxed: 3 minutes for five puzzles.
• Standard: 90 seconds.
• Challenge: 45 seconds.

You can undo one step, clear the expression, request a new puzzle, or reveal a solution for 10 points. Stop if play causes headache, distress, dizziness, or unusual fatigue.

Possible general benefits

Mental arithmetic can practice attention, working memory, planning, and flexible problem solving. A game score does not measure cognitive health and improvement in the game does not prove a clinical benefit.