Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 424 · 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. 1.849 − 799 =
2. 2.924 − 398 =
3. 3.754 − 699 =
4. 4.649 − 299 =
5. 5.404 − 198 =
6. 6.613 − 459 =
7. 7.514 − 199 =
8. 8.667 − 588 =
9. 9.469 − 419 =
10. 10.843 − 379 =
11. 11.990 − 399 =
12. 12.966 − 187 =
13. 13.891 − 699 =
14. 14.655 − 597 =
15. 15.815 − 459 =
16. 16.939 − 398 =
17. 17.713 − 599 =
18. 18.516 − 297 =
19. 19.867 − 197 =
20. 20.399 − 197 =
21. 21.532 − 299 =
22. 22.702 − 397 =
23. 23.785 − 699 =
24. 24.960 − 677 =
25. 25.695 − 199 =
26. 26.314 − 298 =
27. 27.924 − 138 =
28. 28.715 − 497 =
29. 29.770 − 329 =
30. 30.479 − 219 =
31. 31.583 − 268 =
32. 32.953 − 488 =
33. 33.675 − 599 =
34. 34.714 − 369 =
35. 35.945 − 798 =
36. 36.784 − 638 =
37. 37.874 − 797 =
38. 38.870 − 798 =
39. 39.836 − 499 =
40. 40.943 − 798 =

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