Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 223 · 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. 1.906 − 618 =
2. 2.890 − 798 =
3. 3.895 − 799 =
4. 4.719 − 378 =
5. 5.871 − 799 =
6. 6.819 − 697 =
7. 7.897 − 699 =
8. 8.734 − 608 =
9. 9.716 − 699 =
10. 10.748 − 699 =
11. 11.677 − 469 =
12. 12.197 − 149 =
13. 13.762 − 698 =
14. 14.802 − 297 =
15. 15.719 − 299 =
16. 16.919 − 169 =
17. 17.838 − 308 =
18. 18.823 − 527 =
19. 19.687 − 438 =
20. 20.720 − 698 =
21. 21.704 − 299 =
22. 22.802 − 187 =
23. 23.629 − 299 =
24. 24.682 − 659 =
25. 25.984 − 498 =
26. 26.817 − 799 =
27. 27.948 − 128 =
28. 28.970 − 399 =
29. 29.869 − 288 =
30. 30.736 − 308 =
31. 31.996 − 198 =
32. 32.780 − 648 =
33. 33.999 − 677 =
34. 34.715 − 398 =
35. 35.902 − 507 =
36. 36.702 − 399 =
37. 37.592 − 198 =
38. 38.416 − 399 =
39. 39.988 − 799 =
40. 40.473 − 299 =

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