3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 388 · 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. 1.152 + 503 =
2. 2.918 − 381 =
3. 3.689 − 327 =
4. 4.927 − 779 =
5. 5.281 + 196 =
6. 6.241 + 653 =
7. 7.568 + 449 =
8. 8.400 + 215 =
9. 9.612 − 405 =
10. 10.827 − 378 =
11. 11.573 + 133 =
12. 12.562 + 432 =
13. 13.904 − 696 =
14. 14.271 + 637 =
15. 15.670 + 384 =
16. 16.163 + 306 =
17. 17.508 − 387 =
18. 18.786 − 359 =
19. 19.475 + 214 =
20. 20.183 + 254 =
21. 21.603 − 117 =
22. 22.982 − 146 =
23. 23.551 + 479 =
24. 24.485 − 168 =
25. 25.505 − 374 =
26. 26.735 − 575 =
27. 27.248 + 288 =
28. 28.524 − 177 =
29. 29.686 + 267 =
30. 30.794 − 453 =
31. 31.719 − 328 =
32. 32.640 + 636 =
33. 33.243 + 231 =
34. 34.235 + 163 =
35. 35.688 + 309 =
36. 36.858 − 208 =
37. 37.938 − 785 =
38. 38.789 − 605 =
39. 39.468 + 136 =
40. 40.376 + 183 =

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