Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 225 · 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. 1.991 − 319 =
2. 2.708 − 419 =
3. 3.765 − 387 =
4. 4.682 − 597 =
5. 5.657 − 588 =
6. 6.687 − 359 =
7. 7.926 − 147 =
8. 8.968 − 198 =
9. 9.750 − 597 =
10. 10.624 − 359 =
11. 11.977 − 497 =
12. 12.737 − 697 =
13. 13.605 − 407 =
14. 14.887 − 397 =
15. 15.967 − 497 =
16. 16.878 − 178 =
17. 17.481 − 197 =
18. 18.699 − 397 =
19. 19.938 − 699 =
20. 20.710 − 598 =
21. 21.227 − 199 =
22. 22.820 − 197 =
23. 23.710 − 299 =
24. 24.860 − 189 =
25. 25.898 − 218 =
26. 26.952 − 698 =
27. 27.873 − 119 =
28. 28.685 − 469 =
29. 29.799 − 677 =
30. 30.754 − 197 =
31. 31.638 − 557 =
32. 32.891 − 798 =
33. 33.871 − 137 =
34. 34.984 − 798 =
35. 35.545 − 499 =
36. 36.277 − 197 =
37. 37.404 − 198 =
38. 38.780 − 398 =
39. 39.551 − 448 =
40. 40.839 − 438 =

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