Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 153 · 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. 1.641 − 169 =
2. 2.572 − 299 =
3. 3.300 − 117 =
4. 4.846 − 598 =
5. 5.847 − 797 =
6. 6.646 − 628 =
7. 7.973 − 799 =
8. 8.882 − 797 =
9. 9.715 − 127 =
10. 10.761 − 697 =
11. 11.645 − 138 =
12. 12.651 − 517 =
13. 13.852 − 528 =
14. 14.929 − 128 =
15. 15.903 − 698 =
16. 16.692 − 497 =
17. 17.841 − 598 =
18. 18.927 − 797 =
19. 19.672 − 347 =
20. 20.887 − 447 =
21. 21.493 − 219 =
22. 22.477 − 319 =
23. 23.529 − 197 =
24. 24.754 − 508 =
25. 25.680 − 537 =
26. 26.892 − 538 =
27. 27.531 − 397 =
28. 28.633 − 579 =
29. 29.665 − 448 =
30. 30.905 − 297 =
31. 31.911 − 497 =
32. 32.470 − 397 =
33. 33.678 − 597 =
34. 34.643 − 218 =
35. 35.984 − 637 =
36. 36.906 − 198 =
37. 37.880 − 297 =
38. 38.631 − 299 =
39. 39.524 − 397 =
40. 40.561 − 398 =

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