Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 3 · 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. 1.932 − 349 =
2. 2.463 − 397 =
3. 3.921 − 128 =
4. 4.655 − 307 =
5. 5.613 − 199 =
6. 6.693 − 569 =
7. 7.648 − 447 =
8. 8.370 − 198 =
9. 9.771 − 199 =
10. 10.870 − 468 =
11. 11.672 − 247 =
12. 12.577 − 419 =
13. 13.876 − 497 =
14. 14.904 − 298 =
15. 15.899 − 257 =
16. 16.862 − 677 =
17. 17.990 − 299 =
18. 18.931 − 517 =
19. 19.620 − 489 =
20. 20.582 − 498 =
21. 21.714 − 349 =
22. 22.776 − 639 =
23. 23.640 − 437 =
24. 24.931 − 599 =
25. 25.739 − 699 =
26. 26.633 − 399 =
27. 27.712 − 698 =
28. 28.357 − 289 =
29. 29.679 − 299 =
30. 30.594 − 198 =
31. 31.993 − 597 =
32. 32.307 − 159 =
33. 33.182 − 127 =
34. 34.465 − 197 =
35. 35.757 − 598 =
36. 36.573 − 519 =
37. 37.614 − 599 =
38. 38.398 − 249 =
39. 39.899 − 699 =
40. 40.234 − 219 =

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