Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 86 · 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. 1.404 − 297 =
2. 2.733 − 618 =
3. 3.321 − 149 =
4. 4.971 − 169 =
5. 5.981 − 797 =
6. 6.828 − 799 =
7. 7.368 − 199 =
8. 8.775 − 119 =
9. 9.839 − 798 =
10. 10.917 − 678 =
11. 11.909 − 238 =
12. 12.697 − 367 =
13. 13.790 − 508 =
14. 14.335 − 298 =
15. 15.925 − 319 =
16. 16.336 − 268 =
17. 17.921 − 148 =
18. 18.714 − 699 =
19. 19.741 − 697 =
20. 20.932 − 497 =
21. 21.405 − 309 =
22. 22.510 − 399 =
23. 23.330 − 297 =
24. 24.854 − 499 =
25. 25.842 − 799 =
26. 26.899 − 547 =
27. 27.841 − 298 =
28. 28.754 − 208 =
29. 29.803 − 397 =
30. 30.716 − 597 =
31. 31.641 − 298 =
32. 32.489 − 278 =
33. 33.351 − 197 =
34. 34.825 − 597 =
35. 35.660 − 399 =
36. 36.594 − 558 =
37. 37.664 − 597 =
38. 38.906 − 599 =
39. 39.891 − 597 =
40. 40.692 − 598 =

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