Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 926 · 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. 1.682 − 597 =
2. 2.241 − 198 =
3. 3.499 − 298 =
4. 4.646 − 498 =
5. 5.325 − 189 =
6. 6.832 − 297 =
7. 7.783 − 337 =
8. 8.865 − 699 =
9. 9.787 − 599 =
10. 10.508 − 458 =
11. 11.365 − 299 =
12. 12.780 − 297 =
13. 13.670 − 399 =
14. 14.958 − 799 =
15. 15.604 − 347 =
16. 16.668 − 318 =
17. 17.746 − 389 =
18. 18.894 − 598 =
19. 19.892 − 798 =
20. 20.953 − 139 =
21. 21.647 − 497 =
22. 22.630 − 579 =
23. 23.931 − 699 =
24. 24.812 − 487 =
25. 25.606 − 398 =
26. 26.662 − 397 =
27. 27.545 − 198 =
28. 28.952 − 397 =
29. 29.749 − 699 =
30. 30.962 − 797 =
31. 31.910 − 258 =
32. 32.656 − 379 =
33. 33.876 − 597 =
34. 34.173 − 158 =
35. 35.833 − 459 =
36. 36.997 − 299 =
37. 37.979 − 499 =
38. 38.850 − 448 =
39. 39.645 − 399 =
40. 40.569 − 399 =

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