Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 151 · 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. 1.657 − 399 =
2. 2.667 − 337 =
3. 3.654 − 639 =
4. 4.704 − 537 =
5. 5.716 − 399 =
6. 6.802 − 298 =
7. 7.490 − 437 =
8. 8.825 − 699 =
9. 9.465 − 128 =
10. 10.402 − 169 =
11. 11.813 − 199 =
12. 12.919 − 668 =
13. 13.517 − 499 =
14. 14.588 − 258 =
15. 15.640 − 599 =
16. 16.671 − 199 =
17. 17.976 − 797 =
18. 18.903 − 447 =
19. 19.818 − 799 =
20. 20.882 − 617 =
21. 21.479 − 297 =
22. 22.609 − 297 =
23. 23.738 − 299 =
24. 24.959 − 697 =
25. 25.808 − 499 =
26. 26.831 − 257 =
27. 27.972 − 687 =
28. 28.854 − 597 =
29. 29.950 − 598 =
30. 30.799 − 408 =
31. 31.901 − 237 =
32. 32.706 − 447 =
33. 33.976 − 698 =
34. 34.706 − 598 =
35. 35.936 − 617 =
36. 36.313 − 137 =
37. 37.643 − 399 =
38. 38.743 − 617 =
39. 39.905 − 538 =
40. 40.884 − 449 =

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