🧱 See It
A circle graph is one whole circle representing 100% of something, cut into slices where each slice's size shows its share of the whole. A class of 20 students got to school today: 10 walked, 6 took the bus, 4 got driven — that's 50%, 30%, and 20%.
✏️ Draw It
Walk (50%), Bus (30%), Car (20%) — three slices, adding up to the whole circle.
🔢 Write It
Every slice's angle at the center comes from its percent:
angle = percent × 360°
For the Walk slice: 50% × 360° = 180° — exactly half the circle.
Every circle graph's slices add up to 100% AND 360° at the exact same time.
💡 Worked Examples
Example 1 — A slice is 25%. Find its angle.
25% × 360° = 90°- Answer: 90° — a quarter of the circle, a right angle at the center.
Example 2 — Two slices are 40% and 35%. Find the third slice's percent and angle.
- All slices add to 100%:
100 − 40 − 35 = 25% - Convert to an angle:
25% × 360° = 90° - Answer: the third slice is 25%, or 90°.
🧠 Quick Reference
To find an angle from a percent: multiply by 360° (or by 3.6, since
360 ÷ 100 = 3.6). Always check that every slice's percent adds up to 100% first — if it doesn't, the graph is wrong before any angle is even calculated.