Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 416 · 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. 1.944 − 497 =
2. 2.836 − 797 =
3. 3.771 − 527 =
4. 4.966 − 638 =
5. 5.986 − 799 =
6. 6.999 − 798 =
7. 7.643 − 257 =
8. 8.265 − 199 =
9. 9.845 − 697 =
10. 10.999 − 799 =
11. 11.837 − 459 =
12. 12.377 − 317 =
13. 13.730 − 599 =
14. 14.893 − 797 =
15. 15.747 − 617 =
16. 16.923 − 578 =
17. 17.408 − 278 =
18. 18.716 − 197 =
19. 19.560 − 397 =
20. 20.898 − 419 =
21. 21.879 − 798 =
22. 22.799 − 198 =
23. 23.350 − 278 =
24. 24.893 − 699 =
25. 25.870 − 799 =
26. 26.979 − 658 =
27. 27.516 − 488 =
28. 28.539 − 197 =
29. 29.621 − 548 =
30. 30.523 − 299 =
31. 31.660 − 128 =
32. 32.277 − 219 =
33. 33.318 − 298 =
34. 34.446 − 249 =
35. 35.759 − 697 =
36. 36.618 − 287 =
37. 37.910 − 199 =
38. 38.700 − 278 =
39. 39.233 − 199 =
40. 40.342 − 298 =

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