Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 906 · 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. 1.783 − 659 =
2. 2.718 − 299 =
3. 3.928 − 268 =
4. 4.545 − 197 =
5. 5.717 − 698 =
6. 6.715 − 589 =
7. 7.768 − 189 =
8. 8.993 − 298 =
9. 9.630 − 497 =
10. 10.425 − 229 =
11. 11.512 − 288 =
12. 12.633 − 197 =
13. 13.877 − 599 =
14. 14.876 − 699 =
15. 15.887 − 257 =
16. 16.915 − 439 =
17. 17.556 − 497 =
18. 18.861 − 798 =
19. 19.704 − 329 =
20. 20.788 − 597 =
21. 21.708 − 248 =
22. 22.426 − 399 =
23. 23.719 − 167 =
24. 24.832 − 397 =
25. 25.767 − 437 =
26. 26.915 − 607 =
27. 27.634 − 299 =
28. 28.897 − 257 =
29. 29.909 − 599 =
30. 30.948 − 497 =
31. 31.640 − 327 =
32. 32.911 − 697 =
33. 33.773 − 198 =
34. 34.684 − 597 =
35. 35.661 − 437 =
36. 36.559 − 498 =
37. 37.998 − 799 =
38. 38.802 − 299 =
39. 39.891 − 398 =
40. 40.874 − 148 =

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