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Estimate and boundTactic

Tactic

Estimate and bound

Know the answer's size before you compute it

9 min 6 stepsGraded practice at the end

A rough guess can convict a wrong answer before the calculator weighs in. I used to size up the teachers' candy jar the same way, for worse reasons.

Meet it
Spot it
Run it
Dodge the traps
Play with it
Prove it

The first step is free. A free account opens the rest.

Calls on

Signs and order of operationsFactKeep every sign and do the steps in order
Square roots, cube roots, and estimatesFactTrap any root between two perfect powers

Used by

Choose a routeHabitPick the fastest route first; switch when it stalls
Convert units by factor chainingTacticMultiply by 1 until only the units you want are left