Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 374 · 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. 1.854 − 687 =
2. 2.551 − 238 =
3. 3.855 − 798 =
4. 4.542 − 408 =
5. 5.700 − 657 =
6. 6.791 − 699 =
7. 7.533 − 299 =
8. 8.932 − 507 =
9. 9.788 − 397 =
10. 10.837 − 597 =
11. 11.929 − 798 =
12. 12.786 − 617 =
13. 13.717 − 297 =
14. 14.525 − 249 =
15. 15.659 − 319 =
16. 16.926 − 498 =
17. 17.395 − 298 =
18. 18.289 − 199 =
19. 19.437 − 367 =
20. 20.169 − 119 =
21. 21.428 − 399 =
22. 22.820 − 428 =
23. 23.898 − 497 =
24. 24.591 − 199 =
25. 25.629 − 497 =
26. 26.896 − 799 =
27. 27.812 − 599 =
28. 28.538 − 398 =
29. 29.619 − 199 =
30. 30.850 − 799 =
31. 31.787 − 199 =
32. 32.919 − 537 =
33. 33.936 − 199 =
34. 34.800 − 509 =
35. 35.792 − 149 =
36. 36.701 − 508 =
37. 37.787 − 537 =
38. 38.660 − 597 =
39. 39.942 − 299 =
40. 40.810 − 697 =

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