Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 169 · 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. 1.323 − 239 =
2. 2.423 − 297 =
3. 3.439 − 417 =
4. 4.528 − 198 =
5. 5.901 − 799 =
6. 6.833 − 539 =
7. 7.969 − 557 =
8. 8.662 − 478 =
9. 9.941 − 397 =
10. 10.688 − 298 =
11. 11.645 − 398 =
12. 12.564 − 479 =
13. 13.689 − 407 =
14. 14.859 − 197 =
15. 15.908 − 439 =
16. 16.601 − 287 =
17. 17.950 − 237 =
18. 18.932 − 797 =
19. 19.535 − 519 =
20. 20.547 − 399 =
21. 21.884 − 498 =
22. 22.766 − 699 =
23. 23.935 − 699 =
24. 24.951 − 298 =
25. 25.701 − 638 =
26. 26.991 − 798 =
27. 27.331 − 249 =
28. 28.977 − 798 =
29. 29.387 − 298 =
30. 30.941 − 797 =
31. 31.716 − 697 =
32. 32.793 − 627 =
33. 33.393 − 248 =
34. 34.685 − 639 =
35. 35.896 − 578 =
36. 36.848 − 497 =
37. 37.436 − 139 =
38. 38.861 − 498 =
39. 39.571 − 298 =
40. 40.856 − 599 =

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