Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 867 · 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. 1.609 − 199 =
2. 2.603 − 499 =
3. 3.322 − 149 =
4. 4.943 − 797 =
5. 5.551 − 297 =
6. 6.850 − 599 =
7. 7.875 − 127 =
8. 8.691 − 498 =
9. 9.487 − 399 =
10. 10.368 − 169 =
11. 11.739 − 697 =
12. 12.336 − 299 =
13. 13.417 − 319 =
14. 14.342 − 297 =
15. 15.780 − 399 =
16. 16.692 − 499 =
17. 17.336 − 119 =
18. 18.589 − 397 =
19. 19.590 − 429 =
20. 20.900 − 799 =
21. 21.917 − 529 =
22. 22.524 − 298 =
23. 23.920 − 387 =
24. 24.782 − 337 =
25. 25.749 − 299 =
26. 26.848 − 799 =
27. 27.940 − 338 =
28. 28.675 − 257 =
29. 29.428 − 199 =
30. 30.934 − 199 =
31. 31.434 − 337 =
32. 32.861 − 797 =
33. 33.620 − 498 =
34. 34.651 − 579 =
35. 35.982 − 597 =
36. 36.640 − 597 =
37. 37.631 − 347 =
38. 38.188 − 117 =
39. 39.608 − 559 =
40. 40.588 − 129 =

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