Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 382 · 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. 1.958 − 438 =
2. 2.796 − 699 =
3. 3.727 − 199 =
4. 4.834 − 339 =
5. 5.486 − 259 =
6. 6.624 − 497 =
7. 7.795 − 398 =
8. 8.631 − 397 =
9. 9.980 − 378 =
10. 10.856 − 389 =
11. 11.836 − 319 =
12. 12.690 − 338 =
13. 13.954 − 667 =
14. 14.569 − 497 =
15. 15.895 − 488 =
16. 16.751 − 698 =
17. 17.748 − 298 =
18. 18.847 − 297 =
19. 19.632 − 449 =
20. 20.433 − 249 =
21. 21.746 − 497 =
22. 22.924 − 297 =
23. 23.763 − 698 =
24. 24.645 − 199 =
25. 25.653 − 159 =
26. 26.838 − 699 =
27. 27.885 − 799 =
28. 28.619 − 398 =
29. 29.445 − 399 =
30. 30.887 − 599 =
31. 31.723 − 497 =
32. 32.771 − 599 =
33. 33.938 − 798 =
34. 34.469 − 248 =
35. 35.813 − 799 =
36. 36.865 − 399 =
37. 37.328 − 208 =
38. 38.930 − 497 =
39. 39.601 − 407 =
40. 40.327 − 299 =

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