Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 186 · 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. 1.812 − 398 =
2. 2.799 − 608 =
3. 3.640 − 427 =
4. 4.856 − 489 =
5. 5.892 − 198 =
6. 6.465 − 449 =
7. 7.664 − 199 =
8. 8.498 − 247 =
9. 9.788 − 297 =
10. 10.697 − 198 =
11. 11.769 − 409 =
12. 12.698 − 499 =
13. 13.922 − 799 =
14. 14.407 − 197 =
15. 15.369 − 198 =
16. 16.958 − 497 =
17. 17.631 − 199 =
18. 18.542 − 499 =
19. 19.730 − 549 =
20. 20.629 − 197 =
21. 21.545 − 409 =
22. 22.749 − 397 =
23. 23.708 − 568 =
24. 24.671 − 507 =
25. 25.666 − 599 =
26. 26.351 − 118 =
27. 27.693 − 509 =
28. 28.623 − 379 =
29. 29.874 − 548 =
30. 30.544 − 479 =
31. 31.863 − 297 =
32. 32.816 − 298 =
33. 33.286 − 258 =
34. 34.263 − 198 =
35. 35.704 − 258 =
36. 36.572 − 399 =
37. 37.990 − 457 =
38. 38.814 − 799 =
39. 39.891 − 397 =
40. 40.924 − 127 =

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