Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 737 · 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. 1.787 − 429 =
2. 2.875 − 797 =
3. 3.709 − 339 =
4. 4.937 − 599 =
5. 5.988 − 669 =
6. 6.295 − 228 =
7. 7.891 − 699 =
8. 8.907 − 798 =
9. 9.582 − 498 =
10. 10.388 − 197 =
11. 11.641 − 258 =
12. 12.617 − 149 =
13. 13.732 − 278 =
14. 14.780 − 297 =
15. 15.437 − 118 =
16. 16.819 − 799 =
17. 17.900 − 597 =
18. 18.570 − 227 =
19. 19.913 − 477 =
20. 20.241 − 179 =
21. 21.951 − 397 =
22. 22.802 − 497 =
23. 23.412 − 397 =
24. 24.513 − 297 =
25. 25.670 − 618 =
26. 26.762 − 298 =
27. 27.446 − 367 =
28. 28.489 − 407 =
29. 29.738 − 499 =
30. 30.720 − 367 =
31. 31.719 − 289 =
32. 32.165 − 127 =
33. 33.816 − 277 =
34. 34.806 − 599 =
35. 35.757 − 597 =
36. 36.534 − 398 =
37. 37.494 − 398 =
38. 38.886 − 318 =
39. 39.953 − 298 =
40. 40.939 − 579 =

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