Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 994 · 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 − 798 =
2. 2.710 − 149 =
3. 3.800 − 299 =
4. 4.442 − 198 =
5. 5.922 − 368 =
6. 6.854 − 338 =
7. 7.622 − 598 =
8. 8.848 − 199 =
9. 9.413 − 299 =
10. 10.838 − 589 =
11. 11.731 − 299 =
12. 12.654 − 298 =
13. 13.417 − 388 =
14. 14.654 − 607 =
15. 15.808 − 499 =
16. 16.844 − 597 =
17. 17.938 − 398 =
18. 18.782 − 677 =
19. 19.827 − 659 =
20. 20.971 − 549 =
21. 21.948 − 698 =
22. 22.774 − 299 =
23. 23.686 − 497 =
24. 24.914 − 498 =
25. 25.903 − 798 =
26. 26.440 − 399 =
27. 27.933 − 178 =
28. 28.277 − 228 =
29. 29.774 − 478 =
30. 30.652 − 297 =
31. 31.697 − 227 =
32. 32.415 − 358 =
33. 33.999 − 397 =
34. 34.936 − 369 =
35. 35.537 − 179 =
36. 36.323 − 199 =
37. 37.730 − 397 =
38. 38.828 − 667 =
39. 39.783 − 639 =
40. 40.762 − 689 =

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