Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 84 · 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. 1.990 − 688 =
2. 2.995 − 249 =
3. 3.451 − 427 =
4. 4.517 − 398 =
5. 5.300 − 197 =
6. 6.949 − 329 =
7. 7.704 − 668 =
8. 8.457 − 398 =
9. 9.842 − 579 =
10. 10.617 − 499 =
11. 11.765 − 369 =
12. 12.819 − 698 =
13. 13.311 − 177 =
14. 14.656 − 387 =
15. 15.807 − 297 =
16. 16.934 − 699 =
17. 17.795 − 638 =
18. 18.715 − 499 =
19. 19.433 − 379 =
20. 20.880 − 697 =
21. 21.685 − 658 =
22. 22.527 − 497 =
23. 23.825 − 449 =
24. 24.640 − 239 =
25. 25.588 − 499 =
26. 26.724 − 498 =
27. 27.958 − 619 =
28. 28.771 − 399 =
29. 29.834 − 588 =
30. 30.436 − 197 =
31. 31.816 − 699 =
32. 32.247 − 148 =
33. 33.928 − 697 =
34. 34.955 − 198 =
35. 35.621 − 488 =
36. 36.940 − 797 =
37. 37.516 − 447 =
38. 38.982 − 297 =
39. 39.884 − 797 =
40. 40.391 − 198 =

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