3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 453 · 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. 1.444 − 344 =
2. 2.174 + 413 =
3. 3.716 + 121 =
4. 4.141 + 238 =
5. 5.582 − 303 =
6. 6.484 + 297 =
7. 7.639 + 482 =
8. 8.956 − 489 =
9. 9.510 − 159 =
10. 10.271 + 505 =
11. 11.524 − 339 =
12. 12.291 + 319 =
13. 13.224 + 272 =
14. 14.416 + 211 =
15. 15.609 − 319 =
16. 16.772 + 267 =
17. 17.333 + 116 =
18. 18.901 − 773 =
19. 19.158 + 344 =
20. 20.307 + 146 =
21. 21.546 − 258 =
22. 22.862 − 269 =
23. 23.927 − 508 =
24. 24.351 + 466 =
25. 25.450 − 291 =
26. 26.885 − 506 =
27. 27.713 + 505 =
28. 28.530 + 513 =
29. 29.226 + 146 =
30. 30.645 + 239 =
31. 31.733 + 489 =
32. 32.909 − 417 =
33. 33.855 − 525 =
34. 34.174 + 315 =
35. 35.530 − 177 =
36. 36.524 − 355 =
37. 37.160 + 151 =
38. 38.590 − 284 =
39. 39.553 + 305 =
40. 40.594 − 494 =

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