Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 268 · 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. 1.653 − 299 =
2. 2.999 − 698 =
3. 3.828 − 259 =
4. 4.565 − 419 =
5. 5.749 − 199 =
6. 6.905 − 297 =
7. 7.908 − 689 =
8. 8.894 − 428 =
9. 9.718 − 198 =
10. 10.380 − 197 =
11. 11.770 − 198 =
12. 12.831 − 427 =
13. 13.818 − 698 =
14. 14.791 − 498 =
15. 15.929 − 599 =
16. 16.862 − 798 =
17. 17.705 − 599 =
18. 18.711 − 677 =
19. 19.886 − 698 =
20. 20.932 − 639 =
21. 21.663 − 598 =
22. 22.346 − 198 =
23. 23.931 − 597 =
24. 24.383 − 249 =
25. 25.944 − 189 =
26. 26.992 − 599 =
27. 27.773 − 597 =
28. 28.212 − 198 =
29. 29.823 − 397 =
30. 30.876 − 399 =
31. 31.587 − 467 =
32. 32.713 − 299 =
33. 33.415 − 158 =
34. 34.665 − 499 =
35. 35.429 − 399 =
36. 36.974 − 597 =
37. 37.501 − 398 =
38. 38.777 − 399 =
39. 39.782 − 509 =
40. 40.680 − 499 =

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