Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 445 · 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. 1.665 − 447 =
2. 2.642 − 177 =
3. 3.519 − 198 =
4. 4.947 − 398 =
5. 5.989 − 569 =
6. 6.450 − 388 =
7. 7.968 − 797 =
8. 8.599 − 568 =
9. 9.495 − 248 =
10. 10.928 − 399 =
11. 11.925 − 499 =
12. 12.826 − 799 =
13. 13.919 − 197 =
14. 14.643 − 599 =
15. 15.497 − 388 =
16. 16.720 − 177 =
17. 17.617 − 158 =
18. 18.675 − 598 =
19. 19.632 − 597 =
20. 20.753 − 258 =
21. 21.692 − 197 =
22. 22.934 − 297 =
23. 23.753 − 257 =
24. 24.746 − 699 =
25. 25.802 − 699 =
26. 26.854 − 527 =
27. 27.532 − 397 =
28. 28.446 − 298 =
29. 29.577 − 398 =
30. 30.834 − 798 =
31. 31.618 − 499 =
32. 32.512 − 238 =
33. 33.842 − 797 =
34. 34.796 − 697 =
35. 35.865 − 799 =
36. 36.588 − 537 =
37. 37.918 − 608 =
38. 38.715 − 599 =
39. 39.973 − 199 =
40. 40.703 − 677 =

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