Simple Pie Charts — Revision Notes

⚡ 30-Second Revision

Revision checked 17 October 2026.

360° = 100% = whole.
Part = total × angle/360.
Total = part × 360/angle.
Within one pie, ratios use angles directly.
Category-to-rest uses the complement.

2-Minute Revision

For one pie, convert among angle, share and amount. A 72-degree sector is one fifth; if it represents 48 objects, the whole is 240. Missing angles subtract from 360, while missing percentages subtract from 100. A 60-degree category has ratio 1:6 to the whole and 1:5 to the rest. Keep those denominators distinct.

5-Minute Revision

Original drill: A 600-unit pie has sectors 108°, 90°, 72° and a remainder. Their amounts are 180, 150, 120 and 150. The remainder is 90°. The first category exceeds the second by 30 units, or 20 percent of the second. Its share exceeds the second share by 5 percentage points. Reconstruct the whole by adding the amounts and the circle by adding the angles. Both checks should agree.

Vyyuha Quick Recall

PART: Pin down the whole; Align label units; Reduce the fraction; Test by reversing the calculation.