Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 87 · 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. 1.955 − 398 =
2. 2.954 − 798 =
3. 3.918 − 298 =
4. 4.773 − 458 =
5. 5.887 − 399 =
6. 6.916 − 398 =
7. 7.316 − 217 =
8. 8.777 − 497 =
9. 9.605 − 397 =
10. 10.996 − 797 =
11. 11.928 − 238 =
12. 12.736 − 697 =
13. 13.829 − 589 =
14. 14.787 − 567 =
15. 15.947 − 218 =
16. 16.985 − 299 =
17. 17.762 − 297 =
18. 18.802 − 499 =
19. 19.457 − 199 =
20. 20.473 − 197 =
21. 21.829 − 199 =
22. 22.820 − 628 =
23. 23.757 − 437 =
24. 24.312 − 299 =
25. 25.505 − 299 =
26. 26.927 − 797 =
27. 27.823 − 487 =
28. 28.405 − 197 =
29. 29.491 − 299 =
30. 30.766 − 198 =
31. 31.577 − 517 =
32. 32.987 − 599 =
33. 33.925 − 197 =
34. 34.964 − 598 =
35. 35.682 − 497 =
36. 36.623 − 498 =
37. 37.412 − 199 =
38. 38.459 − 359 =
39. 39.241 − 199 =
40. 40.504 − 267 =

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