Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 217 · 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. 1.926 − 198 =
2. 2.750 − 508 =
3. 3.603 − 167 =
4. 4.692 − 597 =
5. 5.551 − 267 =
6. 6.797 − 617 =
7. 7.952 − 598 =
8. 8.718 − 558 =
9. 9.947 − 297 =
10. 10.936 − 467 =
11. 11.752 − 639 =
12. 12.748 − 697 =
13. 13.546 − 358 =
14. 14.900 − 199 =
15. 15.784 − 587 =
16. 16.858 − 447 =
17. 17.954 − 798 =
18. 18.675 − 397 =
19. 19.406 − 298 =
20. 20.540 − 398 =
21. 21.602 − 299 =
22. 22.927 − 498 =
23. 23.636 − 438 =
24. 24.516 − 498 =
25. 25.612 − 197 =
26. 26.395 − 198 =
27. 27.377 − 139 =
28. 28.458 − 399 =
29. 29.695 − 498 =
30. 30.797 − 678 =
31. 31.501 − 298 =
32. 32.802 − 399 =
33. 33.640 − 397 =
34. 34.868 − 398 =
35. 35.889 − 277 =
36. 36.902 − 377 =
37. 37.669 − 399 =
38. 38.942 − 437 =
39. 39.647 − 388 =
40. 40.743 − 397 =

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