Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 551 · 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. 1.827 − 798 =
2. 2.710 − 189 =
3. 3.940 − 798 =
4. 4.989 − 428 =
5. 5.238 − 197 =
6. 6.665 − 199 =
7. 7.757 − 697 =
8. 8.991 − 498 =
9. 9.880 − 698 =
10. 10.990 − 628 =
11. 11.859 − 399 =
12. 12.462 − 439 =
13. 13.815 − 627 =
14. 14.458 − 199 =
15. 15.563 − 147 =
16. 16.816 − 799 =
17. 17.800 − 698 =
18. 18.752 − 697 =
19. 19.824 − 698 =
20. 20.562 − 447 =
21. 21.362 − 318 =
22. 22.790 − 439 =
23. 23.742 − 599 =
24. 24.676 − 258 =
25. 25.799 − 397 =
26. 26.618 − 497 =
27. 27.708 − 488 =
28. 28.449 − 199 =
29. 29.907 − 648 =
30. 30.865 − 798 =
31. 31.996 − 798 =
32. 32.394 − 179 =
33. 33.975 − 698 =
34. 34.235 − 198 =
35. 35.444 − 299 =
36. 36.991 − 699 =
37. 37.698 − 179 =
38. 38.535 − 298 =
39. 39.867 − 627 =
40. 40.403 − 168 =

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