Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 212 · 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. 1.796 − 399 =
2. 2.803 − 597 =
3. 3.980 − 697 =
4. 4.439 − 397 =
5. 5.981 − 798 =
6. 6.910 − 297 =
7. 7.314 − 199 =
8. 8.999 − 299 =
9. 9.619 − 199 =
10. 10.804 − 608 =
11. 11.277 − 198 =
12. 12.761 − 507 =
13. 13.988 − 588 =
14. 14.952 − 597 =
15. 15.977 − 629 =
16. 16.955 − 339 =
17. 17.521 − 198 =
18. 18.783 − 299 =
19. 19.698 − 198 =
20. 20.750 − 597 =
21. 21.818 − 397 =
22. 22.665 − 348 =
23. 23.460 − 388 =
24. 24.827 − 698 =
25. 25.998 − 797 =
26. 26.964 − 299 =
27. 27.843 − 698 =
28. 28.755 − 247 =
29. 29.220 − 198 =
30. 30.711 − 519 =
31. 31.929 − 197 =
32. 32.935 − 159 =
33. 33.600 − 548 =
34. 34.333 − 199 =
35. 35.264 − 198 =
36. 36.648 − 499 =
37. 37.737 − 397 =
38. 38.739 − 197 =
39. 39.726 − 588 =
40. 40.766 − 398 =

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