Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 35 · 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. 1.622 − 487 =
2. 2.791 − 399 =
3. 3.875 − 508 =
4. 4.890 − 399 =
5. 5.662 − 598 =
6. 6.850 − 797 =
7. 7.318 − 297 =
8. 8.903 − 627 =
9. 9.774 − 699 =
10. 10.828 − 437 =
11. 11.538 − 318 =
12. 12.514 − 438 =
13. 13.609 − 499 =
14. 14.586 − 467 =
15. 15.750 − 647 =
16. 16.940 − 428 =
17. 17.706 − 549 =
18. 18.763 − 689 =
19. 19.614 − 459 =
20. 20.399 − 367 =
21. 21.368 − 298 =
22. 22.544 − 227 =
23. 23.412 − 298 =
24. 24.681 − 397 =
25. 25.565 − 198 =
26. 26.450 − 297 =
27. 27.909 − 697 =
28. 28.629 − 217 =
29. 29.769 − 299 =
30. 30.766 − 279 =
31. 31.782 − 279 =
32. 32.329 − 299 =
33. 33.818 − 298 =
34. 34.966 − 558 =
35. 35.677 − 628 =
36. 36.280 − 159 =
37. 37.803 − 498 =
38. 38.842 − 398 =
39. 39.920 − 348 =
40. 40.931 − 698 =

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