Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 490 · 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. 1.769 − 257 =
2. 2.903 − 637 =
3. 3.331 − 298 =
4. 4.647 − 319 =
5. 5.853 − 497 =
6. 6.229 − 198 =
7. 7.778 − 628 =
8. 8.934 − 699 =
9. 9.468 − 367 =
10. 10.503 − 259 =
11. 11.925 − 697 =
12. 12.449 − 398 =
13. 13.417 − 367 =
14. 14.887 − 798 =
15. 15.571 − 347 =
16. 16.891 − 197 =
17. 17.833 − 197 =
18. 18.517 − 169 =
19. 19.578 − 369 =
20. 20.529 − 419 =
21. 21.825 − 599 =
22. 22.611 − 198 =
23. 23.815 − 389 =
24. 24.876 − 397 =
25. 25.522 − 398 =
26. 26.998 − 477 =
27. 27.551 − 248 =
28. 28.640 − 398 =
29. 29.713 − 577 =
30. 30.461 − 308 =
31. 31.750 − 679 =
32. 32.814 − 599 =
33. 33.471 − 397 =
34. 34.377 − 129 =
35. 35.719 − 419 =
36. 36.623 − 298 =
37. 37.610 − 478 =
38. 38.955 − 467 =
39. 39.519 − 409 =
40. 40.847 − 418 =

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