Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 135 · 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. 1.863 − 299 =
2. 2.924 − 149 =
3. 3.609 − 198 =
4. 4.561 − 499 =
5. 5.985 − 197 =
6. 6.643 − 498 =
7. 7.931 − 647 =
8. 8.367 − 269 =
9. 9.844 − 697 =
10. 10.323 − 199 =
11. 11.697 − 498 =
12. 12.587 − 398 =
13. 13.813 − 598 =
14. 14.457 − 197 =
15. 15.438 − 299 =
16. 16.922 − 199 =
17. 17.902 − 798 =
18. 18.932 − 577 =
19. 19.802 − 519 =
20. 20.594 − 499 =
21. 21.289 − 219 =
22. 22.591 − 399 =
23. 23.380 − 297 =
24. 24.284 − 199 =
25. 25.335 − 209 =
26. 26.885 − 519 =
27. 27.880 − 599 =
28. 28.567 − 197 =
29. 29.208 − 169 =
30. 30.756 − 557 =
31. 31.781 − 198 =
32. 32.967 − 699 =
33. 33.750 − 679 =
34. 34.715 − 698 =
35. 35.851 − 598 =
36. 36.928 − 797 =
37. 37.436 − 299 =
38. 38.938 − 397 =
39. 39.933 − 567 =
40. 40.830 − 578 =

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