Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 85 · 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. 1.722 − 398 =
2. 2.934 − 797 =
3. 3.545 − 487 =
4. 4.882 − 397 =
5. 5.919 − 698 =
6. 6.943 − 589 =
7. 7.992 − 198 =
8. 8.802 − 497 =
9. 9.480 − 297 =
10. 10.808 − 557 =
11. 11.604 − 498 =
12. 12.718 − 317 =
13. 13.943 − 619 =
14. 14.740 − 517 =
15. 15.752 − 499 =
16. 16.752 − 298 =
17. 17.496 − 449 =
18. 18.938 − 399 =
19. 19.988 − 419 =
20. 20.887 − 199 =
21. 21.979 − 638 =
22. 22.955 − 498 =
23. 23.705 − 497 =
24. 24.595 − 399 =
25. 25.804 − 197 =
26. 26.631 − 398 =
27. 27.693 − 199 =
28. 28.425 − 249 =
29. 29.522 − 499 =
30. 30.547 − 499 =
31. 31.363 − 299 =
32. 32.703 − 509 =
33. 33.979 − 378 =
34. 34.350 − 199 =
35. 35.885 − 167 =
36. 36.423 − 279 =
37. 37.362 − 298 =
38. 38.733 − 697 =
39. 39.873 − 799 =
40. 40.812 − 599 =

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