Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 720 · 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. 1.998 − 347 =
2. 2.882 − 397 =
3. 3.851 − 278 =
4. 4.473 − 199 =
5. 5.438 − 338 =
6. 6.380 − 299 =
7. 7.960 − 199 =
8. 8.766 − 668 =
9. 9.864 − 257 =
10. 10.527 − 157 =
11. 11.722 − 187 =
12. 12.312 − 299 =
13. 13.570 − 298 =
14. 14.974 − 698 =
15. 15.807 − 459 =
16. 16.591 − 498 =
17. 17.558 − 528 =
18. 18.318 − 298 =
19. 19.634 − 198 =
20. 20.484 − 399 =
21. 21.352 − 197 =
22. 22.885 − 698 =
23. 23.726 − 597 =
24. 24.821 − 698 =
25. 25.354 − 229 =
26. 26.835 − 698 =
27. 27.898 − 558 =
28. 28.724 − 499 =
29. 29.371 − 117 =
30. 30.308 − 197 =
31. 31.859 − 699 =
32. 32.940 − 498 =
33. 33.725 − 499 =
34. 34.986 − 549 =
35. 35.452 − 409 =
36. 36.670 − 538 =
37. 37.911 − 797 =
38. 38.946 − 799 =
39. 39.931 − 799 =
40. 40.700 − 329 =

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