Morning/ Afternoon Work
Checking calculations by doing the inverse
Miss Hall has completed some addition calculations. However, she is not sure whether they are correct or not.
Check Miss Hall's Homework by doing the inverse.
What is the inverse to addition?
That's right! It's subtraction.
- is the inverse to +
So if 156 + 333 = 489 then 489 - 333 = 156.
Also, if 333 + 156 = 489 then 489 - 156 = 333.
Miss Hall's Homework
Are Miss Hall's calculations correct or incorrect?
1. Copy out the addition calculation.
2. Write the inverse subtraction calculation.
3. Use column subtraction to check if the calculation is correct or incorrect.
4. Put a tick next to the calculation if it is correct or a cross if it is incorrect.
1. 1708 + 456 = 2164
2. 5647 + 3454 = 9101
3. 589 + 7987 = 8572
4. 4709 + 1898 = 6607
5. 3321 + 3793 = 7111