Area by subtraction (shaded regions)

When a shaded region is what is left after removing something, find the whole and the removed part separately and subtract. Trying to measure the odd-shaped remainder directly is almost always the harder route.

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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 ladder1 problem. Three in a row finishes it.0/3 in a row · 0/1 solved
Practice — 5-point ladder1 problem. Three in a row finishes it.0/3 in a row · 0/1 solved
Skill quizFinish every ladder that has problems first.Finish the ladders above first

Before and after

Needs first

GEO-01Perimeter and area of rectilinear shapes

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Nothing yet. No other skill in the Atlas lists this one as a prerequisite.

In official papers

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