Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 682 · 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. 1.904 − 499 =
2. 2.931 − 389 =
3. 3.882 − 798 =
4. 4.309 − 198 =
5. 5.245 − 199 =
6. 6.574 − 238 =
7. 7.526 − 168 =
8. 8.457 − 397 =
9. 9.829 − 637 =
10. 10.767 − 177 =
11. 11.821 − 697 =
12. 12.792 − 497 =
13. 13.779 − 398 =
14. 14.966 − 799 =
15. 15.606 − 308 =
16. 16.770 − 398 =
17. 17.739 − 369 =
18. 18.465 − 197 =
19. 19.911 − 297 =
20. 20.864 − 298 =
21. 21.863 − 598 =
22. 22.887 − 299 =
23. 23.640 − 199 =
24. 24.588 − 498 =
25. 25.780 − 679 =
26. 26.314 − 277 =
27. 27.907 − 298 =
28. 28.891 − 597 =
29. 29.554 − 499 =
30. 30.592 − 219 =
31. 31.771 − 358 =
32. 32.481 − 148 =
33. 33.418 − 299 =
34. 34.931 − 588 =
35. 35.826 − 799 =
36. 36.271 − 198 =
37. 37.797 − 598 =
38. 38.552 − 197 =
39. 39.962 − 408 =
40. 40.772 − 599 =

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