Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 257 · 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. 1.818 − 697 =
2. 2.996 − 599 =
3. 3.951 − 799 =
4. 4.821 − 407 =
5. 5.637 − 339 =
6. 6.697 − 348 =
7. 7.415 − 397 =
8. 8.839 − 379 =
9. 9.798 − 627 =
10. 10.679 − 598 =
11. 11.934 − 499 =
12. 12.744 − 637 =
13. 13.807 − 318 =
14. 14.907 − 597 =
15. 15.576 − 448 =
16. 16.918 − 189 =
17. 17.766 − 697 =
18. 18.943 − 567 =
19. 19.848 − 799 =
20. 20.413 − 398 =
21. 21.227 − 199 =
22. 22.625 − 597 =
23. 23.819 − 397 =
24. 24.339 − 317 =
25. 25.527 − 198 =
26. 26.858 − 799 =
27. 27.842 − 699 =
28. 28.748 − 569 =
29. 29.894 − 299 =
30. 30.479 − 397 =
31. 31.463 − 247 =
32. 32.506 − 397 =
33. 33.409 − 198 =
34. 34.982 − 498 =
35. 35.483 − 368 =
36. 36.917 − 187 =
37. 37.751 − 199 =
38. 38.561 − 378 =
39. 39.988 − 157 =
40. 40.856 − 337 =

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