Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 404 · 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 − 298 =
2. 2.403 − 367 =
3. 3.561 − 299 =
4. 4.710 − 509 =
5. 5.702 − 598 =
6. 6.968 − 319 =
7. 7.555 − 148 =
8. 8.855 − 199 =
9. 9.635 − 497 =
10. 10.764 − 619 =
11. 11.788 − 699 =
12. 12.996 − 697 =
13. 13.672 − 297 =
14. 14.865 − 799 =
15. 15.870 − 239 =
16. 16.974 − 229 =
17. 17.688 − 628 =
18. 18.753 − 537 =
19. 19.717 − 697 =
20. 20.653 − 499 =
21. 21.337 − 299 =
22. 22.958 − 498 =
23. 23.921 − 319 =
24. 24.997 − 399 =
25. 25.986 − 279 =
26. 26.623 − 597 =
27. 27.821 − 199 =
28. 28.705 − 278 =
29. 29.927 − 658 =
30. 30.424 − 199 =
31. 31.635 − 498 =
32. 32.969 − 137 =
33. 33.635 − 439 =
34. 34.775 − 699 =
35. 35.650 − 458 =
36. 36.638 − 438 =
37. 37.323 − 228 =
38. 38.905 − 297 =
39. 39.928 − 587 =
40. 40.695 − 398 =

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