Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 352 · 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. 1.717 − 468 =
2. 2.732 − 139 =
3. 3.475 − 438 =
4. 4.469 − 348 =
5. 5.917 − 657 =
6. 6.938 − 479 =
7. 7.773 − 297 =
8. 8.602 − 428 =
9. 9.783 − 377 =
10. 10.860 − 199 =
11. 11.871 − 657 =
12. 12.763 − 697 =
13. 13.894 − 387 =
14. 14.665 − 269 =
15. 15.275 − 189 =
16. 16.834 − 197 =
17. 17.560 − 229 =
18. 18.891 − 197 =
19. 19.691 − 299 =
20. 20.857 − 139 =
21. 21.822 − 279 =
22. 22.938 − 798 =
23. 23.277 − 157 =
24. 24.447 − 399 =
25. 25.685 − 568 =
26. 26.672 − 188 =
27. 27.613 − 398 =
28. 28.539 − 498 =
29. 29.370 − 299 =
30. 30.392 − 297 =
31. 31.881 − 368 =
32. 32.988 − 598 =
33. 33.737 − 399 =
34. 34.689 − 599 =
35. 35.479 − 448 =
36. 36.479 − 398 =
37. 37.830 − 407 =
38. 38.678 − 597 =
39. 39.612 − 398 =
40. 40.997 − 597 =

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