Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 52 · 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. 1.709 − 599 =
2. 2.315 − 119 =
3. 3.699 − 518 =
4. 4.956 − 799 =
5. 5.882 − 498 =
6. 6.817 − 499 =
7. 7.545 − 499 =
8. 8.456 − 298 =
9. 9.830 − 799 =
10. 10.789 − 667 =
11. 11.476 − 449 =
12. 12.520 − 297 =
13. 13.994 − 599 =
14. 14.912 − 699 =
15. 15.761 − 499 =
16. 16.545 − 299 =
17. 17.714 − 129 =
18. 18.367 − 149 =
19. 19.850 − 148 =
20. 20.362 − 337 =
21. 21.692 − 399 =
22. 22.572 − 459 =
23. 23.538 − 397 =
24. 24.467 − 119 =
25. 25.811 − 297 =
26. 26.373 − 298 =
27. 27.700 − 148 =
28. 28.715 − 597 =
29. 29.870 − 497 =
30. 30.934 − 298 =
31. 31.927 − 219 =
32. 32.897 − 499 =
33. 33.674 − 199 =
34. 34.768 − 699 =
35. 35.916 − 698 =
36. 36.962 − 497 =
37. 37.689 − 507 =
38. 38.498 − 369 =
39. 39.686 − 509 =
40. 40.775 − 397 =

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