Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 609 · 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. 1.445 − 319 =
2. 2.989 − 669 =
3. 3.737 − 199 =
4. 4.865 − 398 =
5. 5.700 − 499 =
6. 6.800 − 697 =
7. 7.826 − 797 =
8. 8.575 − 458 =
9. 9.500 − 129 =
10. 10.978 − 398 =
11. 11.661 − 579 =
12. 12.518 − 168 =
13. 13.723 − 399 =
14. 14.780 − 679 =
15. 15.378 − 318 =
16. 16.886 − 679 =
17. 17.531 − 297 =
18. 18.897 − 399 =
19. 19.545 − 498 =
20. 20.773 − 689 =
21. 21.777 − 599 =
22. 22.624 − 198 =
23. 23.451 − 399 =
24. 24.602 − 247 =
25. 25.842 − 699 =
26. 26.630 − 499 =
27. 27.280 − 198 =
28. 28.770 − 199 =
29. 29.378 − 298 =
30. 30.538 − 147 =
31. 31.638 − 389 =
32. 32.563 − 499 =
33. 33.887 − 399 =
34. 34.972 − 139 =
35. 35.950 − 429 =
36. 36.631 − 499 =
37. 37.830 − 497 =
38. 38.817 − 359 =
39. 39.835 − 387 =
40. 40.839 − 597 =

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