Percent Stack Game
Calculate successive percentage increases and discounts accurately.
Math puzzle challenges
Loading percentages challenge…
Instructions, device progress and accessibility
Choose Practice or UTC Daily mode and select a difficulty. Use keyboard, touch, Tab, and Enter with the controls. Wrong checks reduce score; Hint and Undo mark assisted rounds. There is no required sign-in, and results remain on this device.
Local progress is checked when play begins.
How to play Percent Stack
Read the starting amount and apply every percentage change in the order shown. Each increase or decrease uses the updated amount, not the original starting amount. Type your final dollar total.
The mathematics behind the game
A percent increase of p% multiplies an amount by 1 + p/100, while a decrease multiplies by 1 − p/100. The game rounds each intermediate currency total to cents.
Worked example
Start at $80.00, increase 25% to $100.00, then decrease 10% to $90.00. The answer is not $92.00 because the second change uses $100 rather than $80.
Tips to improve
Try Easy first to learn the steps without a timer. Move to Normal and Hard for larger numbers and more tasks. If you make a mistake, use Undo to reconsider the last move. A hint gives useful guidance but does not set an unaided personal best. Daily challenges offer the same seeded puzzle each UTC day on this device.
Frequently asked questions
Does an increase followed by the same decrease cancel out?
No. A 20% increase and a 20% decrease compound to a 4% loss.
How should I round?
Round to the nearest cent after each percentage step, as shown in the puzzle instructions.