Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 596 · 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. 1.979 − 597 =
2. 2.983 − 797 =
3. 3.911 − 507 =
4. 4.495 − 328 =
5. 5.955 − 697 =
6. 6.615 − 598 =
7. 7.440 − 418 =
8. 8.830 − 397 =
9. 9.775 − 338 =
10. 10.765 − 699 =
11. 11.908 − 498 =
12. 12.630 − 298 =
13. 13.729 − 698 =
14. 14.724 − 699 =
15. 15.750 − 399 =
16. 16.506 − 347 =
17. 17.756 − 598 =
18. 18.847 − 467 =
19. 19.949 − 797 =
20. 20.814 − 699 =
21. 21.861 − 797 =
22. 22.916 − 569 =
23. 23.244 − 228 =
24. 24.713 − 398 =
25. 25.628 − 299 =
26. 26.871 − 468 =
27. 27.990 − 698 =
28. 28.794 − 679 =
29. 29.839 − 797 =
30. 30.445 − 197 =
31. 31.933 − 427 =
32. 32.902 − 799 =
33. 33.917 − 299 =
34. 34.869 − 649 =
35. 35.992 − 368 =
36. 36.515 − 328 =
37. 37.873 − 799 =
38. 38.588 − 499 =
39. 39.870 − 597 =
40. 40.748 − 689 =

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