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“Percent” literally means per hundred. So 40% of 25 asks: cut 25 into 100 equal parts, then keep 40 of them.
Every rule arrives with its why.
A plain-spoken walkthrough that builds the idea from scratch and shows why each rule works.
Free · no sign-up · in 3 languages
MathPrisma is a free interactive course that takes you from arithmetic foundations all the way to test-day mastery. Every lesson teaches the why, every widget lets you play with the idea, and endless auto-checked practice makes it stick.
y=2x+1
m=63=2
Six stages, from arithmetic foundations to test day. Start where you are.
“Percent” literally means per hundred. So 40% of 25 asks: cut 25 into 100 equal parts, then keep 40 of them.
Every rule arrives with its why.
A plain-spoken walkthrough that builds the idea from scratch and shows why each rule works.
40% × 25 = 10
Hands-on tools — draggable graphs, live calculators, visual models — to build real intuition.
Endless auto-generated questions that check your work, track a streak, and reveal every step.
On the roadmap
Once the curriculum has done its job, Test Readiness takes over: timed modules, full-length sections, error analytics, and drilling tools built to turn skill into score.
Mixed practice will be free. The advanced toolkit will be a one-time purchase that keeps the rest of the site free for everyone.
Preview Test Readiness →The whole course is free and always will be. A small donation helps keep it growing.