Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 418 · 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. 1.601 − 297 =
2. 2.313 − 128 =
3. 3.699 − 279 =
4. 4.211 − 148 =
5. 5.627 − 599 =
6. 6.984 − 398 =
7. 7.935 − 599 =
8. 8.372 − 197 =
9. 9.883 − 797 =
10. 10.827 − 559 =
11. 11.666 − 298 =
12. 12.893 − 197 =
13. 13.425 − 168 =
14. 14.902 − 697 =
15. 15.965 − 259 =
16. 16.895 − 399 =
17. 17.665 − 328 =
18. 18.427 − 137 =
19. 19.731 − 599 =
20. 20.745 − 397 =
21. 21.747 − 468 =
22. 22.738 − 547 =
23. 23.449 − 298 =
24. 24.558 − 279 =
25. 25.985 − 799 =
26. 26.473 − 397 =
27. 27.345 − 127 =
28. 28.774 − 219 =
29. 29.994 − 667 =
30. 30.597 − 568 =
31. 31.925 − 499 =
32. 32.903 − 799 =
33. 33.905 − 337 =
34. 34.825 − 647 =
35. 35.771 − 699 =
36. 36.837 − 397 =
37. 37.747 − 297 =
38. 38.816 − 699 =
39. 39.844 − 799 =
40. 40.658 − 539 =

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