Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 12 · 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. 1.921 − 367 =
2. 2.636 − 299 =
3. 3.507 − 249 =
4. 4.975 − 798 =
5. 5.959 − 598 =
6. 6.278 − 199 =
7. 7.992 − 598 =
8. 8.937 − 299 =
9. 9.586 − 538 =
10. 10.847 − 547 =
11. 11.873 − 397 =
12. 12.231 − 199 =
13. 13.875 − 537 =
14. 14.977 − 699 =
15. 15.554 − 138 =
16. 16.723 − 487 =
17. 17.767 − 609 =
18. 18.349 − 298 =
19. 19.875 − 799 =
20. 20.337 − 298 =
21. 21.712 − 448 =
22. 22.785 − 207 =
23. 23.542 − 209 =
24. 24.409 − 157 =
25. 25.368 − 188 =
26. 26.365 − 338 =
27. 27.671 − 499 =
28. 28.852 − 678 =
29. 29.580 − 148 =
30. 30.435 − 397 =
31. 31.746 − 197 =
32. 32.409 − 299 =
33. 33.716 − 498 =
34. 34.457 − 197 =
35. 35.921 − 298 =
36. 36.949 − 287 =
37. 37.716 − 439 =
38. 38.883 − 597 =
39. 39.586 − 497 =
40. 40.471 − 198 =

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