A family's monthly budget of ₹60,000 is shown in a pie chart: rent 30%, food 25%, transport 10%, savings 20%, others 15%. What is the central angle for food, and how much more is spent on rent than saved?

A pie chart splits 360 degrees in the same proportions as the money. So 1% of the total is 3.6 degrees. Most pie chart questions only need two conversions: percent to degrees (multiply by 3.6) and percent to rupees (multiply by the total, divide by 100). For a difference between two slices, subtract the percentages first, then convert once.

Data: Total ₹60,000. Rent 30%, food 25%, transport 10%, savings 20%, others 15%.

1. Food angle = 25 x 3.6 = 90 degrees.
2. Rent - savings = (30% - 20%) of 60,000 = 10% of 60,000 = ₹6,000.
3. Rent angle = 30 x 3.6 = 108 degrees; savings angle = 72 degrees.
4. If a slice has an angle of 54 degrees, it is 54 / 3.6 = 15% (others), which is ₹9,000.

const total = 60000;
const pct = { rent: 30, food: 25, transport: 10, savings: 20, others: 15 };
console.log(pct.food * 3.6); // Output: 90
console.log(((pct.rent - pct.savings) * total) / 100); // Output: 6000

Always check that the percentages add to 100 (or angles to 360) before using them.

• Converting each slice to rupees separately and then subtracting, which is slower and invites slips.
• Using 100 degrees instead of 360 for the whole pie.