Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 313 · 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. 1.651 − 629 =
2. 2.658 − 497 =
3. 3.421 − 197 =
4. 4.864 − 699 =
5. 5.490 − 168 =
6. 6.672 − 497 =
7. 7.987 − 797 =
8. 8.423 − 387 =
9. 9.794 − 597 =
10. 10.844 − 697 =
11. 11.817 − 159 =
12. 12.628 − 309 =
13. 13.824 − 507 =
14. 14.790 − 698 =
15. 15.816 − 599 =
16. 16.379 − 197 =
17. 17.463 − 398 =
18. 18.873 − 799 =
19. 19.380 − 298 =
20. 20.417 − 147 =
21. 21.797 − 698 =
22. 22.675 − 389 =
23. 23.491 − 189 =
24. 24.924 − 598 =
25. 25.818 − 627 =
26. 26.592 − 399 =
27. 27.737 − 179 =
28. 28.309 − 198 =
29. 29.749 − 668 =
30. 30.736 − 499 =
31. 31.479 − 228 =
32. 32.779 − 698 =
33. 33.672 − 647 =
34. 34.828 − 697 =
35. 35.237 − 178 =
36. 36.945 − 299 =
37. 37.503 − 338 =
38. 38.764 − 378 =
39. 39.869 − 638 =
40. 40.991 − 798 =

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