Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 378 · 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. 1.713 − 499 =
2. 2.300 − 138 =
3. 3.823 − 498 =
4. 4.979 − 798 =
5. 5.484 − 429 =
6. 6.938 − 397 =
7. 7.782 − 199 =
8. 8.938 − 498 =
9. 9.926 − 227 =
10. 10.496 − 197 =
11. 11.667 − 197 =
12. 12.761 − 698 =
13. 13.521 − 317 =
14. 14.747 − 549 =
15. 15.807 − 697 =
16. 16.474 − 298 =
17. 17.752 − 599 =
18. 18.943 − 598 =
19. 19.725 − 398 =
20. 20.906 − 258 =
21. 21.345 − 268 =
22. 22.549 − 128 =
23. 23.418 − 199 =
24. 24.600 − 197 =
25. 25.837 − 599 =
26. 26.822 − 398 =
27. 27.755 − 499 =
28. 28.766 − 429 =
29. 29.934 − 799 =
30. 30.599 − 359 =
31. 31.601 − 197 =
32. 32.981 − 327 =
33. 33.960 − 398 =
34. 34.722 − 699 =
35. 35.528 − 399 =
36. 36.872 − 798 =
37. 37.931 − 137 =
38. 38.841 − 407 =
39. 39.964 − 799 =
40. 40.884 − 129 =

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