Take an expression apart one operation at a time, pick the right step in the right order, or follow a false trail that never reaches the true answer.
Each puzzle is an arithmetic expression you reduce step by step. Choose the operation with the highest precedence available right now, multiply and divide before add and subtract, ties resolve left to right, and innermost parentheses come first. A wrong choice still combines two numbers, but it steers you onto a false trail whose final value won't match the intended answer. Reduce a round of puzzles correctly to finish.
Precedence drills the order of operations by making every out-of-order choice visibly derail the answer, so the rules stick through cause and effect.
Reducing an expression by repeatedly choosing the highest-precedence operation available is the order of operations executed by hand: brackets first, then multiply and divide, then add and subtract, ties left to right.
The original design is that a wrong choice still combines two numbers. Nothing is rejected; the expression simply steers somewhere else.
That is a better teacher than an error message. Precedence is a set of conventions rather than a mathematical necessity, and seeing a legal-looking step produce the wrong final value shows why the convention has to be agreed in advance.
Precedence is an original, free browser math game that drills the order of operations by making every out-of-order choice visibly derail the answer. No install or account needed.