Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 220 · 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. 1.729 − 599 =
2. 2.650 − 297 =
3. 3.868 − 198 =
4. 4.535 − 499 =
5. 5.819 − 139 =
6. 6.874 − 219 =
7. 7.686 − 599 =
8. 8.837 − 397 =
9. 9.688 − 599 =
10. 10.774 − 497 =
11. 11.780 − 378 =
12. 12.934 − 168 =
13. 13.387 − 229 =
14. 14.286 − 199 =
15. 15.960 − 298 =
16. 16.351 − 279 =
17. 17.725 − 698 =
18. 18.629 − 597 =
19. 19.920 − 389 =
20. 20.722 − 628 =
21. 21.871 − 799 =
22. 22.922 − 258 =
23. 23.874 − 317 =
24. 24.959 − 669 =
25. 25.704 − 269 =
26. 26.544 − 369 =
27. 27.626 − 298 =
28. 28.473 − 438 =
29. 29.447 − 287 =
30. 30.468 − 298 =
31. 31.777 − 358 =
32. 32.755 − 499 =
33. 33.736 − 698 =
34. 34.986 − 399 =
35. 35.752 − 498 =
36. 36.654 − 499 =
37. 37.780 − 298 =
38. 38.578 − 349 =
39. 39.608 − 178 =
40. 40.994 − 299 =

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