Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 200 · 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. 1.919 − 398 =
2. 2.866 − 699 =
3. 3.763 − 678 =
4. 4.515 − 298 =
5. 5.997 − 667 =
6. 6.680 − 408 =
7. 7.662 − 199 =
8. 8.686 − 639 =
9. 9.252 − 228 =
10. 10.855 − 228 =
11. 11.855 − 427 =
12. 12.969 − 347 =
13. 13.642 − 398 =
14. 14.590 − 219 =
15. 15.946 − 429 =
16. 16.966 − 588 =
17. 17.546 − 369 =
18. 18.580 − 519 =
19. 19.914 − 387 =
20. 20.869 − 217 =
21. 21.715 − 498 =
22. 22.421 − 118 =
23. 23.733 − 198 =
24. 24.894 − 607 =
25. 25.484 − 299 =
26. 26.894 − 658 =
27. 27.805 − 168 =
28. 28.344 − 299 =
29. 29.709 − 599 =
30. 30.723 − 598 =
31. 31.933 − 698 =
32. 32.794 − 298 =
33. 33.988 − 697 =
34. 34.779 − 339 =
35. 35.950 − 298 =
36. 36.508 − 398 =
37. 37.961 − 199 =
38. 38.700 − 557 =
39. 39.804 − 598 =
40. 40.578 − 458 =

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