Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 149 · 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. 1.625 − 397 =
2. 2.842 − 798 =
3. 3.784 − 517 =
4. 4.667 − 407 =
5. 5.405 − 298 =
6. 6.289 − 267 =
7. 7.993 − 678 =
8. 8.514 − 299 =
9. 9.531 − 197 =
10. 10.508 − 198 =
11. 11.810 − 477 =
12. 12.765 − 437 =
13. 13.881 − 798 =
14. 14.957 − 597 =
15. 15.470 − 398 =
16. 16.421 − 397 =
17. 17.970 − 199 =
18. 18.584 − 357 =
19. 19.578 − 498 =
20. 20.747 − 697 =
21. 21.525 − 438 =
22. 22.719 − 649 =
23. 23.719 − 459 =
24. 24.764 − 549 =
25. 25.973 − 508 =
26. 26.863 − 597 =
27. 27.967 − 699 =
28. 28.857 − 598 =
29. 29.831 − 198 =
30. 30.681 − 269 =
31. 31.644 − 498 =
32. 32.895 − 689 =
33. 33.426 − 289 =
34. 34.595 − 297 =
35. 35.538 − 297 =
36. 36.947 − 498 =
37. 37.676 − 599 =
38. 38.439 − 169 =
39. 39.463 − 188 =
40. 40.811 − 437 =

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