Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 532 · 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. 1.496 − 439 =
2. 2.335 − 299 =
3. 3.891 − 697 =
4. 4.636 − 238 =
5. 5.585 − 297 =
6. 6.898 − 697 =
7. 7.847 − 598 =
8. 8.944 − 799 =
9. 9.784 − 698 =
10. 10.327 − 229 =
11. 11.893 − 698 =
12. 12.852 − 599 =
13. 13.938 − 297 =
14. 14.882 − 669 =
15. 15.302 − 189 =
16. 16.752 − 299 =
17. 17.687 − 138 =
18. 18.667 − 627 =
19. 19.848 − 539 =
20. 20.746 − 279 =
21. 21.644 − 597 =
22. 22.677 − 547 =
23. 23.798 − 629 =
24. 24.983 − 539 =
25. 25.826 − 599 =
26. 26.791 − 168 =
27. 27.956 − 329 =
28. 28.683 − 598 =
29. 29.701 − 657 =
30. 30.816 − 798 =
31. 31.779 − 239 =
32. 32.922 − 497 =
33. 33.443 − 398 =
34. 34.997 − 497 =
35. 35.917 − 497 =
36. 36.855 − 397 =
37. 37.572 − 448 =
38. 38.550 − 299 =
39. 39.530 − 429 =
40. 40.818 − 199 =

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