Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 343 · 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. 1.445 − 387 =
2. 2.675 − 457 =
3. 3.751 − 398 =
4. 4.855 − 697 =
5. 5.253 − 197 =
6. 6.540 − 438 =
7. 7.204 − 127 =
8. 8.984 − 158 =
9. 9.250 − 229 =
10. 10.800 − 398 =
11. 11.943 − 698 =
12. 12.674 − 297 =
13. 13.602 − 589 =
14. 14.712 − 599 =
15. 15.532 − 389 =
16. 16.873 − 697 =
17. 17.992 − 638 =
18. 18.824 − 499 =
19. 19.762 − 698 =
20. 20.479 − 199 =
21. 21.591 − 518 =
22. 22.691 − 219 =
23. 23.707 − 497 =
24. 24.927 − 797 =
25. 25.584 − 479 =
26. 26.505 − 297 =
27. 27.331 − 298 =
28. 28.461 − 227 =
29. 29.937 − 799 =
30. 30.731 − 508 =
31. 31.605 − 297 =
32. 32.679 − 598 =
33. 33.906 − 598 =
34. 34.407 − 198 =
35. 35.613 − 198 =
36. 36.924 − 599 =
37. 37.899 − 799 =
38. 38.563 − 429 =
39. 39.910 − 599 =
40. 40.650 − 597 =

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