Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 9 · 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. 1.749 − 399 =
2. 2.909 − 498 =
3. 3.907 − 589 =
4. 4.546 − 527 =
5. 5.795 − 697 =
6. 6.171 − 139 =
7. 7.295 − 227 =
8. 8.946 − 497 =
9. 9.901 − 619 =
10. 10.468 − 398 =
11. 11.666 − 157 =
12. 12.661 − 248 =
13. 13.480 − 438 =
14. 14.245 − 229 =
15. 15.387 − 348 =
16. 16.893 − 198 =
17. 17.653 − 617 =
18. 18.835 − 579 =
19. 19.328 − 209 =
20. 20.440 − 219 =
21. 21.836 − 797 =
22. 22.539 − 457 =
23. 23.503 − 239 =
24. 24.675 − 517 =
25. 25.623 − 179 =
26. 26.773 − 297 =
27. 27.984 − 679 =
28. 28.546 − 197 =
29. 29.502 − 169 =
30. 30.398 − 309 =
31. 31.784 − 627 =
32. 32.540 − 299 =
33. 33.837 − 197 =
34. 34.836 − 369 =
35. 35.282 − 198 =
36. 36.794 − 569 =
37. 37.872 − 529 =
38. 38.527 − 467 =
39. 39.839 − 797 =
40. 40.523 − 118 =

Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths