Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 406 · 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. 1.561 − 438 =
2. 2.563 − 509 =
3. 3.745 − 399 =
4. 4.639 − 519 =
5. 5.517 − 198 =
6. 6.936 − 798 =
7. 7.530 − 397 =
8. 8.600 − 398 =
9. 9.556 − 317 =
10. 10.348 − 197 =
11. 11.829 − 798 =
12. 12.896 − 399 =
13. 13.886 − 798 =
14. 14.428 − 198 =
15. 15.734 − 498 =
16. 16.826 − 797 =
17. 17.829 − 679 =
18. 18.852 − 598 =
19. 19.437 − 119 =
20. 20.904 − 399 =
21. 21.847 − 549 =
22. 22.798 − 589 =
23. 23.921 − 298 =
24. 24.731 − 599 =
25. 25.520 − 219 =
26. 26.607 − 208 =
27. 27.701 − 397 =
28. 28.909 − 209 =
29. 29.692 − 389 =
30. 30.433 − 288 =
31. 31.481 − 297 =
32. 32.468 − 118 =
33. 33.984 − 298 =
34. 34.344 − 199 =
35. 35.955 − 698 =
36. 36.957 − 399 =
37. 37.963 − 519 =
38. 38.732 − 517 =
39. 39.689 − 559 =
40. 40.617 − 448 =

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