Eliminate impossible choices by bounding

Before calculating, ask how big the answer could possibly be and how small. Choices outside those bounds go immediately. Even when bounding does not name the answer, going from five choices to two changes what a guess is worth.

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Work through it

LearnWhat it is, how to spot it, a worked example, and where it goes wrong.
Practice — 3-point ladderNo problems written at this tier yet.Nothing written at this tier yet
Practice — 4-point ladder2 problems. Three in a row finishes it.0/3 in a row · 0/2 solved
Practice — 5-point ladder2 problems. Three in a row finishes it.0/3 in a row · 0/2 solved
Skill quizFinish every ladder that has problems first.Finish the ladders above first

Before and after

Needs first

CFT-01Find what is actually being asked NUM-12Estimation and order of magnitude

Opens up

CFT-06Estimate to the nearest choice CFT-07Spot the trick vs. decide to grind

In official papers

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