Dot problems with minus
You learn to find the missing number under the dot in a subtraction.
How to work it out
- If the dot is at the end, take the answer away from the start.
- If the dot is at the start, add the two numbers together.
70 − · = 45
- The dot is at the end.
- Take the answer away from the starting number: 70 − 45 = 25.
- Check: 70 − 25 = 45.
- The number under the dot is 25.
More examples
· − 25 = 50
- The dot is at the start.
- Add the two numbers together: 50 + 25 = 75.
- The number under the dot is 75.
100 − · = 64
- The dot is at the end.
- Take 64 away from 100: 100 − 64 = 36.
- The number under the dot is 36.