Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 201 · 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. 1.860 − 798 =
2. 2.966 − 499 =
3. 3.828 − 699 =
4. 4.552 − 398 =
5. 5.759 − 498 =
6. 6.489 − 369 =
7. 7.789 − 499 =
8. 8.786 − 239 =
9. 9.597 − 198 =
10. 10.531 − 207 =
11. 11.999 − 449 =
12. 12.847 − 199 =
13. 13.729 − 607 =
14. 14.834 − 299 =
15. 15.651 − 577 =
16. 16.832 − 297 =
17. 17.834 − 359 =
18. 18.623 − 399 =
19. 19.884 − 627 =
20. 20.745 − 299 =
21. 21.894 − 798 =
22. 22.519 − 138 =
23. 23.850 − 398 =
24. 24.726 − 547 =
25. 25.882 − 378 =
26. 26.896 − 199 =
27. 27.838 − 398 =
28. 28.841 − 218 =
29. 29.396 − 318 =
30. 30.763 − 399 =
31. 31.514 − 419 =
32. 32.852 − 798 =
33. 33.575 − 368 =
34. 34.764 − 199 =
35. 35.604 − 337 =
36. 36.637 − 499 =
37. 37.856 − 298 =
38. 38.260 − 199 =
39. 39.971 − 298 =
40. 40.709 − 457 =

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