Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 818 · 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. 1.927 − 697 =
2. 2.749 − 178 =
3. 3.919 − 199 =
4. 4.574 − 528 =
5. 5.864 − 687 =
6. 6.882 − 698 =
7. 7.866 − 198 =
8. 8.961 − 517 =
9. 9.571 − 497 =
10. 10.885 − 159 =
11. 11.881 − 697 =
12. 12.762 − 529 =
13. 13.822 − 259 =
14. 14.918 − 619 =
15. 15.593 − 309 =
16. 16.353 − 157 =
17. 17.982 − 499 =
18. 18.643 − 399 =
19. 19.590 − 497 =
20. 20.767 − 657 =
21. 21.988 − 409 =
22. 22.858 − 697 =
23. 23.437 − 199 =
24. 24.877 − 598 =
25. 25.849 − 529 =
26. 26.760 − 397 =
27. 27.487 − 428 =
28. 28.915 − 399 =
29. 29.990 − 597 =
30. 30.495 − 397 =
31. 31.368 − 127 =
32. 32.971 − 797 =
33. 33.932 − 198 =
34. 34.901 − 378 =
35. 35.779 − 399 =
36. 36.215 − 188 =
37. 37.683 − 589 =
38. 38.787 − 577 =
39. 39.508 − 128 =
40. 40.881 − 129 =

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