Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 492 · 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. 1.881 − 498 =
2. 2.852 − 799 =
3. 3.874 − 409 =
4. 4.942 − 388 =
5. 5.933 − 488 =
6. 6.847 − 397 =
7. 7.456 − 138 =
8. 8.966 − 699 =
9. 9.968 − 489 =
10. 10.923 − 659 =
11. 11.891 − 499 =
12. 12.793 − 597 =
13. 13.337 − 197 =
14. 14.672 − 298 =
15. 15.681 − 199 =
16. 16.718 − 327 =
17. 17.676 − 448 =
18. 18.432 − 278 =
19. 19.924 − 517 =
20. 20.568 − 197 =
21. 21.671 − 197 =
22. 22.723 − 699 =
23. 23.838 − 197 =
24. 24.769 − 528 =
25. 25.778 − 417 =
26. 26.658 − 499 =
27. 27.451 − 297 =
28. 28.624 − 277 =
29. 29.544 − 478 =
30. 30.755 − 428 =
31. 31.797 − 598 =
32. 32.975 − 148 =
33. 33.631 − 598 =
34. 34.527 − 229 =
35. 35.231 − 199 =
36. 36.769 − 697 =
37. 37.875 − 299 =
38. 38.979 − 398 =
39. 39.400 − 257 =
40. 40.841 − 287 =

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