Dial the rate and the years and watch a principal bar grow one yearly interest block at a time to the target line, extend or cut a price bar by a markup or markdown percent, and set the percent error of an estimate against the actual bar.
The island bank stacks a yearly interest block of P × r on top of the principal for every year dialed, so I = P × r × t is built block by block up to the gold target line — and with both dials free, several rate × years pairs reach it. Markup extends a cost bar and markdown cuts it, with the percent always taken of the original cost, while percent-error mode draws the gap between estimate and actual and names the classic slip of dividing by the estimate instead of the actual. Best for Grades 7–8.
A free, no-signup, no-ads math game for Grade 7 — practising simple-interest, markup, markdown, percent-error, percent. Play in your browser on the KidsDoMath games hub or explore more Money & Finance games.
By grade level: 7th Grade Math Games
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What math does Interest Island practice? Interest Island practices Simple Interest, Markup, Markdown, Percent Error. The island bank stacks a yearly interest block of P × r on top of the principal for every year dialed, so I = P × r × t is built block by block up to the gold target line — and with both dials free, several rate × years pairs reach it.
What grade is Interest Island for? Interest Island is built for Grade 7 (ages 12–13). It sits in the Money & Finance strand, and it ramps across 8 levels so younger or older players find their own pace.
How do you play Interest Island? Dial the rate and the years and watch a principal bar grow one yearly interest block at a time to the target line, extend or cut a price bar by a markup or markdown percent, and set the percent error of an estimate against the actual bar.
Is Interest Island free to play? Yes. Interest Island is free, with no ads and no sign-up, and it runs in the browser on a phone, tablet or computer.