Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 432 · 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. 1.392 − 368 =
2. 2.826 − 118 =
3. 3.315 − 299 =
4. 4.639 − 519 =
5. 5.961 − 468 =
6. 6.397 − 199 =
7. 7.939 − 428 =
8. 8.908 − 178 =
9. 9.828 − 498 =
10. 10.738 − 369 =
11. 11.541 − 328 =
12. 12.854 − 649 =
13. 13.927 − 799 =
14. 14.962 − 699 =
15. 15.993 − 497 =
16. 16.846 − 558 =
17. 17.794 − 667 =
18. 18.667 − 197 =
19. 19.815 − 499 =
20. 20.901 − 299 =
21. 21.450 − 378 =
22. 22.790 − 618 =
23. 23.672 − 309 =
24. 24.695 − 599 =
25. 25.550 − 199 =
26. 26.744 − 399 =
27. 27.348 − 298 =
28. 28.593 − 308 =
29. 29.828 − 148 =
30. 30.506 − 267 =
31. 31.410 − 148 =
32. 32.801 − 699 =
33. 33.872 − 198 =
34. 34.620 − 389 =
35. 35.492 − 299 =
36. 36.805 − 298 =
37. 37.944 − 637 =
38. 38.448 − 398 =
39. 39.873 − 269 =
40. 40.840 − 658 =

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