Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 305 · 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. 1.895 − 499 =
2. 2.579 − 458 =
3. 3.897 − 599 =
4. 4.915 − 198 =
5. 5.918 − 309 =
6. 6.606 − 497 =
7. 7.987 − 797 =
8. 8.252 − 199 =
9. 9.976 − 297 =
10. 10.883 − 197 =
11. 11.916 − 199 =
12. 12.386 − 278 =
13. 13.634 − 397 =
14. 14.897 − 268 =
15. 15.900 − 338 =
16. 16.982 − 299 =
17. 17.818 − 597 =
18. 18.428 − 127 =
19. 19.982 − 798 =
20. 20.833 − 599 =
21. 21.968 − 537 =
22. 22.756 − 598 =
23. 23.817 − 797 =
24. 24.586 − 397 =
25. 25.645 − 398 =
26. 26.681 − 197 =
27. 27.942 − 627 =
28. 28.818 − 639 =
29. 29.897 − 798 =
30. 30.993 − 799 =
31. 31.939 − 559 =
32. 32.713 − 299 =
33. 33.716 − 698 =
34. 34.938 − 598 =
35. 35.842 − 397 =
36. 36.517 − 198 =
37. 37.768 − 698 =
38. 38.725 − 228 =
39. 39.770 − 418 =
40. 40.917 − 798 =

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