Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 233 · 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. 1.917 − 217 =
2. 2.836 − 647 =
3. 3.878 − 318 =
4. 4.999 − 799 =
5. 5.636 − 388 =
6. 6.759 − 578 =
7. 7.485 − 229 =
8. 8.725 − 599 =
9. 9.639 − 148 =
10. 10.767 − 497 =
11. 11.760 − 189 =
12. 12.749 − 297 =
13. 13.862 − 639 =
14. 14.547 − 197 =
15. 15.901 − 399 =
16. 16.739 − 528 =
17. 17.831 − 277 =
18. 18.960 − 469 =
19. 19.922 − 798 =
20. 20.941 − 298 =
21. 21.896 − 559 =
22. 22.694 − 509 =
23. 23.855 − 797 =
24. 24.883 − 699 =
25. 25.378 − 299 =
26. 26.921 − 447 =
27. 27.566 − 429 =
28. 28.451 − 399 =
29. 29.894 − 198 =
30. 30.784 − 497 =
31. 31.612 − 198 =
32. 32.673 − 519 =
33. 33.954 − 799 =
34. 34.704 − 299 =
35. 35.942 − 689 =
36. 36.668 − 197 =
37. 37.846 − 499 =
38. 38.528 − 267 =
39. 39.708 − 559 =
40. 40.287 − 198 =

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