Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 871 · 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. 1.998 − 699 =
2. 2.538 − 409 =
3. 3.968 − 599 =
4. 4.223 − 207 =
5. 5.730 − 367 =
6. 6.825 − 138 =
7. 7.860 − 699 =
8. 8.803 − 597 =
9. 9.456 − 198 =
10. 10.852 − 199 =
11. 11.502 − 369 =
12. 12.756 − 599 =
13. 13.264 − 179 =
14. 14.569 − 499 =
15. 15.667 − 508 =
16. 16.638 − 299 =
17. 17.658 − 388 =
18. 18.981 − 639 =
19. 19.636 − 498 =
20. 20.397 − 258 =
21. 21.976 − 497 =
22. 22.421 − 288 =
23. 23.579 − 128 =
24. 24.985 − 629 =
25. 25.595 − 277 =
26. 26.722 − 519 =
27. 27.460 − 329 =
28. 28.909 − 669 =
29. 29.812 − 798 =
30. 30.901 − 597 =
31. 31.573 − 438 =
32. 32.449 − 287 =
33. 33.446 − 299 =
34. 34.953 − 599 =
35. 35.628 − 568 =
36. 36.696 − 269 =
37. 37.826 − 339 =
38. 38.653 − 357 =
39. 39.468 − 287 =
40. 40.194 − 129 =

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