3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 948 · 40 questions

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

1. 1.907 − 485 =
2. 2.868 − 164 =
3. 3.390 + 526 =
4. 4.865 − 351 =
5. 5.684 + 322 =
6. 6.679 − 462 =
7. 7.413 + 241 =
8. 8.665 + 167 =
9. 9.743 + 621 =
10. 10.584 + 651 =
11. 11.510 − 321 =
12. 12.548 + 147 =
13. 13.353 + 643 =
14. 14.306 + 612 =
15. 15.782 − 239 =
16. 16.460 − 353 =
17. 17.664 + 279 =
18. 18.825 − 331 =
19. 19.258 + 321 =
20. 20.654 + 241 =
21. 21.171 + 502 =
22. 22.603 − 456 =
23. 23.423 + 188 =
24. 24.205 + 379 =
25. 25.680 − 248 =
26. 26.917 − 338 =
27. 27.524 − 338 =
28. 28.677 + 421 =
29. 29.739 − 291 =
30. 30.622 + 565 =
31. 31.917 − 645 =
32. 32.861 − 631 =
33. 33.925 − 291 =
34. 34.422 − 168 =
35. 35.157 + 313 =
36. 36.686 + 279 =
37. 37.751 + 641 =
38. 38.383 + 359 =
39. 39.471 + 127 =
40. 40.532 − 377 =

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