Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 842 · 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. 1.960 − 399 =
2. 2.831 − 797 =
3. 3.837 − 597 =
4. 4.627 − 299 =
5. 5.924 − 537 =
6. 6.634 − 608 =
7. 7.479 − 418 =
8. 8.949 − 237 =
9. 9.668 − 308 =
10. 10.883 − 309 =
11. 11.807 − 697 =
12. 12.834 − 658 =
13. 13.640 − 198 =
14. 14.274 − 197 =
15. 15.517 − 398 =
16. 16.930 − 399 =
17. 17.423 − 399 =
18. 18.729 − 387 =
19. 19.335 − 268 =
20. 20.407 − 298 =
21. 21.469 − 297 =
22. 22.442 − 199 =
23. 23.932 − 698 =
24. 24.861 − 498 =
25. 25.925 − 598 =
26. 26.351 − 157 =
27. 27.746 − 367 =
28. 28.937 − 507 =
29. 29.803 − 678 =
30. 30.680 − 279 =
31. 31.678 − 199 =
32. 32.649 − 399 =
33. 33.882 − 199 =
34. 34.801 − 259 =
35. 35.662 − 489 =
36. 36.791 − 388 =
37. 37.622 − 209 =
38. 38.773 − 227 =
39. 39.668 − 639 =
40. 40.683 − 617 =

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