Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 133 · 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. 1.340 − 198 =
2. 2.321 − 257 =
3. 3.930 − 398 =
4. 4.786 − 117 =
5. 5.862 − 797 =
6. 6.569 − 207 =
7. 7.264 − 179 =
8. 8.915 − 378 =
9. 9.510 − 298 =
10. 10.752 − 299 =
11. 11.965 − 798 =
12. 12.550 − 187 =
13. 13.841 − 197 =
14. 14.899 − 569 =
15. 15.947 − 699 =
16. 16.626 − 499 =
17. 17.697 − 198 =
18. 18.864 − 799 =
19. 19.874 − 207 =
20. 20.860 − 597 =
21. 21.852 − 398 =
22. 22.954 − 418 =
23. 23.351 − 169 =
24. 24.792 − 199 =
25. 25.864 − 397 =
26. 26.766 − 438 =
27. 27.869 − 298 =
28. 28.537 − 398 =
29. 29.544 − 268 =
30. 30.319 − 198 =
31. 31.828 − 628 =
32. 32.669 − 188 =
33. 33.550 − 487 =
34. 34.763 − 697 =
35. 35.996 − 798 =
36. 36.755 − 697 =
37. 37.745 − 407 =
38. 38.499 − 269 =
39. 39.814 − 597 =
40. 40.872 − 497 =

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