Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 422 · 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. 1.911 − 218 =
2. 2.762 − 428 =
3. 3.904 − 349 =
4. 4.760 − 288 =
5. 5.336 − 257 =
6. 6.700 − 598 =
7. 7.705 − 199 =
8. 8.772 − 199 =
9. 9.309 − 219 =
10. 10.718 − 129 =
11. 11.254 − 238 =
12. 12.910 − 399 =
13. 13.640 − 499 =
14. 14.329 − 199 =
15. 15.921 − 128 =
16. 16.519 − 397 =
17. 17.596 − 547 =
18. 18.696 − 499 =
19. 19.649 − 628 =
20. 20.822 − 398 =
21. 21.941 − 697 =
22. 22.737 − 499 =
23. 23.542 − 219 =
24. 24.668 − 578 =
25. 25.662 − 639 =
26. 26.715 − 629 =
27. 27.518 − 219 =
28. 28.705 − 229 =
29. 29.418 − 198 =
30. 30.901 − 399 =
31. 31.828 − 799 =
32. 32.244 − 169 =
33. 33.768 − 318 =
34. 34.676 − 498 =
35. 35.948 − 667 =
36. 36.866 − 698 =
37. 37.634 − 268 =
38. 38.755 − 397 =
39. 39.853 − 697 =
40. 40.323 − 199 =

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