Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 689 · 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. 1.299 − 199 =
2. 2.836 − 199 =
3. 3.930 − 199 =
4. 4.230 − 198 =
5. 5.500 − 298 =
6. 6.718 − 198 =
7. 7.833 − 797 =
8. 8.745 − 697 =
9. 9.365 − 199 =
10. 10.545 − 399 =
11. 11.889 − 798 =
12. 12.402 − 377 =
13. 13.760 − 308 =
14. 14.434 − 219 =
15. 15.630 − 398 =
16. 16.662 − 409 =
17. 17.802 − 487 =
18. 18.345 − 199 =
19. 19.960 − 499 =
20. 20.579 − 499 =
21. 21.910 − 699 =
22. 22.731 − 188 =
23. 23.618 − 397 =
24. 24.894 − 299 =
25. 25.693 − 368 =
26. 26.770 − 598 =
27. 27.913 − 198 =
28. 28.644 − 559 =
29. 29.871 − 507 =
30. 30.975 − 467 =
31. 31.341 − 299 =
32. 32.736 − 299 =
33. 33.609 − 498 =
34. 34.649 − 407 =
35. 35.605 − 459 =
36. 36.424 − 349 =
37. 37.775 − 267 =
38. 38.619 − 469 =
39. 39.876 − 797 =
40. 40.321 − 238 =

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