Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 96 · 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. 1.534 − 397 =
2. 2.903 − 597 =
3. 3.849 − 699 =
4. 4.940 − 498 =
5. 5.412 − 198 =
6. 6.935 − 507 =
7. 7.727 − 128 =
8. 8.378 − 299 =
9. 9.659 − 638 =
10. 10.923 − 798 =
11. 11.516 − 298 =
12. 12.524 − 327 =
13. 13.584 − 299 =
14. 14.802 − 559 =
15. 15.689 − 519 =
16. 16.563 − 288 =
17. 17.714 − 617 =
18. 18.710 − 637 =
19. 19.739 − 638 =
20. 20.883 − 449 =
21. 21.535 − 199 =
22. 22.228 − 199 =
23. 23.781 − 247 =
24. 24.817 − 797 =
25. 25.349 − 299 =
26. 26.891 − 799 =
27. 27.480 − 299 =
28. 28.566 − 397 =
29. 29.696 − 599 =
30. 30.804 − 398 =
31. 31.520 − 358 =
32. 32.604 − 477 =
33. 33.926 − 238 =
34. 34.562 − 159 =
35. 35.779 − 589 =
36. 36.540 − 399 =
37. 37.880 − 408 =
38. 38.800 − 369 =
39. 39.246 − 198 =
40. 40.317 − 197 =

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