Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 10 · 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. 1.881 − 649 =
2. 2.669 − 497 =
3. 3.609 − 148 =
4. 4.857 − 797 =
5. 5.943 − 467 =
6. 6.633 − 299 =
7. 7.547 − 168 =
8. 8.292 − 227 =
9. 9.984 − 687 =
10. 10.537 − 279 =
11. 11.758 − 698 =
12. 12.917 − 598 =
13. 13.822 − 508 =
14. 14.807 − 699 =
15. 15.669 − 618 =
16. 16.292 − 169 =
17. 17.192 − 127 =
18. 18.562 − 499 =
19. 19.835 − 487 =
20. 20.859 − 687 =
21. 21.766 − 249 =
22. 22.966 − 547 =
23. 23.251 − 189 =
24. 24.798 − 529 =
25. 25.848 − 499 =
26. 26.793 − 658 =
27. 27.282 − 178 =
28. 28.790 − 397 =
29. 29.978 − 628 =
30. 30.991 − 398 =
31. 31.929 − 588 =
32. 32.642 − 599 =
33. 33.395 − 178 =
34. 34.546 − 528 =
35. 35.840 − 639 =
36. 36.633 − 497 =
37. 37.883 − 449 =
38. 38.951 − 798 =
39. 39.948 − 797 =
40. 40.919 − 697 =

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