3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 67 · 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. 1.631 − 271 =
2. 2.737 − 419 =
3. 3.312 + 297 =
4. 4.714 + 401 =
5. 5.349 + 574 =
6. 6.189 + 362 =
7. 7.563 − 123 =
8. 8.429 + 571 =
9. 9.796 − 403 =
10. 10.424 + 531 =
11. 11.391 + 651 =
12. 12.440 + 586 =
13. 13.304 + 345 =
14. 14.969 − 662 =
15. 15.846 − 232 =
16. 16.788 + 222 =
17. 17.825 − 416 =
18. 18.196 + 568 =
19. 19.828 − 456 =
20. 20.332 + 226 =
21. 21.161 + 579 =
22. 22.321 + 153 =
23. 23.226 + 559 =
24. 24.443 − 131 =
25. 25.607 + 635 =
26. 26.625 − 442 =
27. 27.434 − 171 =
28. 28.787 + 156 =
29. 29.199 + 207 =
30. 30.494 − 366 =
31. 31.950 − 236 =
32. 32.603 − 482 =
33. 33.483 − 132 =
34. 34.820 − 385 =
35. 35.497 + 292 =
36. 36.747 − 149 =
37. 37.669 − 381 =
38. 38.531 − 164 =
39. 39.587 − 221 =
40. 40.402 + 428 =

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