Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 575 · 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. 1.662 − 398 =
2. 2.874 − 797 =
3. 3.620 − 397 =
4. 4.547 − 297 =
5. 5.473 − 299 =
6. 6.650 − 597 =
7. 7.973 − 519 =
8. 8.863 − 639 =
9. 9.692 − 599 =
10. 10.574 − 257 =
11. 11.803 − 389 =
12. 12.745 − 697 =
13. 13.888 − 799 =
14. 14.623 − 389 =
15. 15.439 − 298 =
16. 16.587 − 468 =
17. 17.805 − 498 =
18. 18.755 − 607 =
19. 19.924 − 698 =
20. 20.508 − 198 =
21. 21.569 − 199 =
22. 22.415 − 279 =
23. 23.828 − 437 =
24. 24.847 − 497 =
25. 25.791 − 559 =
26. 26.603 − 378 =
27. 27.307 − 157 =
28. 28.620 − 589 =
29. 29.575 − 328 =
30. 30.637 − 517 =
31. 31.960 − 598 =
32. 32.551 − 348 =
33. 33.836 − 498 =
34. 34.764 − 399 =
35. 35.617 − 499 =
36. 36.895 − 679 =
37. 37.800 − 398 =
38. 38.417 − 199 =
39. 39.649 − 498 =
40. 40.524 − 199 =

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