Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 910 · 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. 1.949 − 499 =
2. 2.465 − 367 =
3. 3.672 − 499 =
4. 4.856 − 697 =
5. 5.863 − 599 =
6. 6.678 − 597 =
7. 7.901 − 798 =
8. 8.748 − 498 =
9. 9.593 − 397 =
10. 10.991 − 698 =
11. 11.795 − 299 =
12. 12.671 − 597 =
13. 13.469 − 299 =
14. 14.857 − 398 =
15. 15.507 − 197 =
16. 16.708 − 437 =
17. 17.839 − 129 =
18. 18.763 − 267 =
19. 19.695 − 578 =
20. 20.906 − 299 =
21. 21.624 − 389 =
22. 22.373 − 269 =
23. 23.874 − 557 =
24. 24.852 − 349 =
25. 25.359 − 199 =
26. 26.709 − 197 =
27. 27.872 − 338 =
28. 28.950 − 498 =
29. 29.922 − 488 =
30. 30.711 − 599 =
31. 31.288 − 267 =
32. 32.602 − 498 =
33. 33.952 − 659 =
34. 34.791 − 697 =
35. 35.891 − 799 =
36. 36.653 − 359 =
37. 37.796 − 399 =
38. 38.348 − 229 =
39. 39.824 − 699 =
40. 40.997 − 598 =

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