Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 373 · 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. 1.365 − 299 =
2. 2.515 − 397 =
3. 3.343 − 268 =
4. 4.845 − 697 =
5. 5.451 − 319 =
6. 6.395 − 247 =
7. 7.895 − 598 =
8. 8.835 − 799 =
9. 9.862 − 618 =
10. 10.840 − 598 =
11. 11.960 − 447 =
12. 12.543 − 297 =
13. 13.744 − 298 =
14. 14.712 − 599 =
15. 15.548 − 219 =
16. 16.946 − 298 =
17. 17.582 − 497 =
18. 18.915 − 498 =
19. 19.713 − 497 =
20. 20.775 − 657 =
21. 21.913 − 288 =
22. 22.853 − 798 =
23. 23.565 − 499 =
24. 24.188 − 149 =
25. 25.775 − 617 =
26. 26.752 − 148 =
27. 27.560 − 199 =
28. 28.961 − 279 =
29. 29.933 − 799 =
30. 30.415 − 138 =
31. 31.684 − 488 =
32. 32.732 − 538 =
33. 33.713 − 568 =
34. 34.639 − 197 =
35. 35.323 − 299 =
36. 36.830 − 599 =
37. 37.776 − 599 =
38. 38.441 − 299 =
39. 39.833 − 799 =
40. 40.395 − 198 =

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