Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 229 · 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. 1.727 − 399 =
2. 2.525 − 157 =
3. 3.310 − 199 =
4. 4.625 − 298 =
5. 5.260 − 168 =
6. 6.484 − 197 =
7. 7.412 − 397 =
8. 8.655 − 597 =
9. 9.995 − 799 =
10. 10.674 − 297 =
11. 11.911 − 798 =
12. 12.825 − 297 =
13. 13.545 − 149 =
14. 14.891 − 317 =
15. 15.326 − 129 =
16. 16.836 − 798 =
17. 17.632 − 338 =
18. 18.371 − 188 =
19. 19.276 − 199 =
20. 20.549 − 249 =
21. 21.626 − 208 =
22. 22.688 − 337 =
23. 23.827 − 229 =
24. 24.983 − 797 =
25. 25.892 − 629 =
26. 26.634 − 599 =
27. 27.440 − 199 =
28. 28.939 − 559 =
29. 29.708 − 488 =
30. 30.912 − 499 =
31. 31.816 − 387 =
32. 32.704 − 617 =
33. 33.443 − 197 =
34. 34.205 − 118 =
35. 35.739 − 599 =
36. 36.393 − 169 =
37. 37.903 − 198 =
38. 38.411 − 299 =
39. 39.941 − 479 =
40. 40.989 − 427 =

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