Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 506 · 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. 1.420 − 279 =
2. 2.997 − 497 =
3. 3.694 − 497 =
4. 4.934 − 298 =
5. 5.967 − 797 =
6. 6.882 − 599 =
7. 7.709 − 478 =
8. 8.669 − 399 =
9. 9.925 − 208 =
10. 10.612 − 339 =
11. 11.996 − 499 =
12. 12.976 − 599 =
13. 13.983 − 698 =
14. 14.969 − 498 =
15. 15.518 − 367 =
16. 16.675 − 317 =
17. 17.357 − 337 =
18. 18.755 − 237 =
19. 19.896 − 499 =
20. 20.838 − 619 =
21. 21.654 − 229 =
22. 22.557 − 499 =
23. 23.829 − 119 =
24. 24.809 − 308 =
25. 25.777 − 509 =
26. 26.865 − 697 =
27. 27.425 − 398 =
28. 28.795 − 698 =
29. 29.982 − 799 =
30. 30.633 − 197 =
31. 31.508 − 198 =
32. 32.911 − 599 =
33. 33.880 − 498 =
34. 34.853 − 658 =
35. 35.723 − 488 =
36. 36.461 − 249 =
37. 37.959 − 129 =
38. 38.946 − 499 =
39. 39.607 − 179 =
40. 40.762 − 618 =

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