Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 34 · 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. 1.906 − 318 =
2. 2.473 − 299 =
3. 3.956 − 599 =
4. 4.789 − 337 =
5. 5.297 − 197 =
6. 6.636 − 218 =
7. 7.673 − 609 =
8. 8.553 − 438 =
9. 9.699 − 598 =
10. 10.836 − 338 =
11. 11.563 − 129 =
12. 12.784 − 388 =
13. 13.628 − 597 =
14. 14.953 − 489 =
15. 15.986 − 678 =
16. 16.709 − 669 =
17. 17.894 − 679 =
18. 18.799 − 199 =
19. 19.492 − 308 =
20. 20.522 − 468 =
21. 21.856 − 398 =
22. 22.586 − 399 =
23. 23.717 − 219 =
24. 24.985 − 247 =
25. 25.320 − 298 =
26. 26.676 − 297 =
27. 27.868 − 269 =
28. 28.704 − 598 =
29. 29.987 − 799 =
30. 30.512 − 299 =
31. 31.709 − 679 =
32. 32.447 − 197 =
33. 33.758 − 299 =
34. 34.983 − 699 =
35. 35.982 − 427 =
36. 36.815 − 288 =
37. 37.618 − 339 =
38. 38.373 − 169 =
39. 39.997 − 199 =
40. 40.863 − 798 =

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