Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 810 · 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. 1.762 − 397 =
2. 2.979 − 648 =
3. 3.644 − 499 =
4. 4.925 − 497 =
5. 5.775 − 297 =
6. 6.276 − 197 =
7. 7.832 − 279 =
8. 8.473 − 198 =
9. 9.797 − 597 =
10. 10.671 − 177 =
11. 11.744 − 637 =
12. 12.933 − 797 =
13. 13.462 − 398 =
14. 14.892 − 699 =
15. 15.800 − 117 =
16. 16.670 − 297 =
17. 17.861 − 499 =
18. 18.361 − 268 =
19. 19.645 − 397 =
20. 20.910 − 269 =
21. 21.881 − 497 =
22. 22.562 − 497 =
23. 23.697 − 168 =
24. 24.738 − 367 =
25. 25.902 − 297 =
26. 26.770 − 607 =
27. 27.953 − 198 =
28. 28.847 − 799 =
29. 29.620 − 238 =
30. 30.393 − 367 =
31. 31.450 − 178 =
32. 32.864 − 797 =
33. 33.973 − 619 =
34. 34.956 − 799 =
35. 35.946 − 799 =
36. 36.601 − 299 =
37. 37.617 − 138 =
38. 38.419 − 299 =
39. 39.732 − 398 =
40. 40.762 − 358 =

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