Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 290 · 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. 1.351 − 307 =
2. 2.507 − 199 =
3. 3.957 − 349 =
4. 4.531 − 498 =
5. 5.425 − 399 =
6. 6.908 − 498 =
7. 7.301 − 199 =
8. 8.446 − 399 =
9. 9.809 − 207 =
10. 10.988 − 597 =
11. 11.718 − 598 =
12. 12.922 − 197 =
13. 13.852 − 467 =
14. 14.856 − 699 =
15. 15.545 − 499 =
16. 16.840 − 498 =
17. 17.888 − 397 =
18. 18.563 − 157 =
19. 19.394 − 199 =
20. 20.769 − 399 =
21. 21.658 − 538 =
22. 22.497 − 357 =
23. 23.732 − 297 =
24. 24.845 − 799 =
25. 25.639 − 368 =
26. 26.914 − 397 =
27. 27.592 − 417 =
28. 28.984 − 598 =
29. 29.385 − 198 =
30. 30.881 − 397 =
31. 31.446 − 169 =
32. 32.684 − 577 =
33. 33.735 − 197 =
34. 34.843 − 497 =
35. 35.577 − 298 =
36. 36.636 − 169 =
37. 37.861 − 798 =
38. 38.628 − 597 =
39. 39.944 − 438 =
40. 40.550 − 298 =

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