Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 834 · 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. 1.840 − 799 =
2. 2.879 − 349 =
3. 3.584 − 398 =
4. 4.719 − 698 =
5. 5.486 − 427 =
6. 6.889 − 597 =
7. 7.823 − 698 =
8. 8.677 − 618 =
9. 9.447 − 299 =
10. 10.977 − 659 =
11. 11.750 − 369 =
12. 12.527 − 278 =
13. 13.713 − 598 =
14. 14.557 − 297 =
15. 15.547 − 399 =
16. 16.752 − 667 =
17. 17.923 − 569 =
18. 18.754 − 597 =
19. 19.665 − 627 =
20. 20.739 − 238 =
21. 21.495 − 459 =
22. 22.776 − 697 =
23. 23.856 − 799 =
24. 24.776 − 299 =
25. 25.735 − 499 =
26. 26.920 − 388 =
27. 27.901 − 498 =
28. 28.656 − 597 =
29. 29.838 − 257 =
30. 30.967 − 799 =
31. 31.622 − 198 =
32. 32.838 − 358 =
33. 33.917 − 549 =
34. 34.753 − 529 =
35. 35.821 − 199 =
36. 36.639 − 518 =
37. 37.532 − 498 =
38. 38.438 − 309 =
39. 39.964 − 687 =
40. 40.715 − 697 =

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