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9×GooGooCalc⌕

Perimeter & Area

The two get mixed up constantly. One is the walk around the edge, the other is the space inside.

Length / base / radius · Width / height

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Grades 4–6

Metric Conversions

The metric staircase. Every step is ten, so converting is just sliding the decimal point.

Grades 4–6

Customary Conversions

Inches, feet, pounds, cups. No pattern to lean on — so go down to the smallest unit and back up.

Grades 3–5

Elapsed Time

Count on to the next whole hour, then the hours, then the leftover minutes. Works every time.

Grades 4–6

Area of Composite Figures

An L-shape is just two rectangles. Slice it, do each piece, add them up.