Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 922 · 40 questions

How to do it in your head (Round up, add back): Round the number you take away up to the next ten or hundred: 297 → 300 (3 too many). Take away the round number. Add back the extra, because you took away too much.

1. 1.946 − 249 =
2. 2.624 − 427 =
3. 3.993 − 199 =
4. 4.975 − 797 =
5. 5.806 − 567 =
6. 6.888 − 797 =
7. 7.272 − 199 =
8. 8.743 − 598 =
9. 9.667 − 599 =
10. 10.762 − 698 =
11. 11.413 − 308 =
12. 12.721 − 199 =
13. 13.558 − 198 =
14. 14.464 − 367 =
15. 15.708 − 598 =
16. 16.427 − 297 =
17. 17.833 − 397 =
18. 18.973 − 619 =
19. 19.577 − 508 =
20. 20.650 − 139 =
21. 21.973 − 797 =
22. 22.621 − 198 =
23. 23.712 − 598 =
24. 24.981 − 129 =
25. 25.718 − 458 =
26. 26.592 − 398 =
27. 27.625 − 379 =
28. 28.497 − 397 =
29. 29.902 − 287 =
30. 30.346 − 297 =
31. 31.809 − 698 =
32. 32.861 − 547 =
33. 33.632 − 489 =
34. 34.930 − 798 =
35. 35.769 − 208 =
36. 36.527 − 499 =
37. 37.745 − 689 =
38. 38.873 − 799 =
39. 39.487 − 199 =
40. 40.730 − 688 =

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