Below zero: money and temperature — Maths trick for kids

The trick

Cross zero — “go to 0 first, then count the rest of the steps”

1. Warmer or more money: move up the number line. Colder or spending: move down.
2. Crossing zero: count the steps to 0 first, then the steps left over.
3. The gap between a number below zero and one above zero: add the two distances from 0.

Use it for: Weather reports, hill-station temperatures, money you owe or are owed, and lifts going below the ground floor.

Worked example: At sunset it was 4 °C. By midnight it was 9 degrees colder. What was it at midnight (°C)? −5

✏️ Practice

Work it out in your head or on paper, then tap your answer — or type it and press Check. Stuck? Press “Show me how”.

🏁 Trick 23 test

20 questions. Check each answer, then go to the next one. Get 16 or more right to pass.

🏅 Sign in with Google to earn the 🌡️ Zero Crosser badge when you pass — and a certificate when you finish all 10 tricks of Part 4 · Clever counting & checking. You can still take the test without signing in.

🖨️ Negative Numbers Worksheet for Kids

• Worksheet set 1 (PDF)
• Worksheet set 2 (PDF)
• Worksheet set 3 (PDF)