3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 22 · 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. 1.402 + 369 =
2. 2.531 + 362 =
3. 3.222 + 567 =
4. 4.857 − 128 =
5. 5.509 + 359 =
6. 6.733 − 181 =
7. 7.637 − 478 =
8. 8.521 − 236 =
9. 9.229 + 627 =
10. 10.784 + 331 =
11. 11.200 + 171 =
12. 12.750 − 256 =
13. 13.509 + 254 =
14. 14.986 − 809 =
15. 15.535 − 216 =
16. 16.661 + 436 =
17. 17.367 + 571 =
18. 18.672 − 475 =
19. 19.415 − 118 =
20. 20.419 − 182 =
21. 21.401 + 373 =
22. 22.848 − 411 =
23. 23.525 − 341 =
24. 24.209 + 188 =
25. 25.691 + 177 =
26. 26.928 − 576 =
27. 27.160 + 498 =
28. 28.423 − 129 =
29. 29.216 + 464 =
30. 30.472 − 156 =
31. 31.688 + 221 =
32. 32.415 − 121 =
33. 33.949 − 669 =
34. 34.520 − 375 =
35. 35.916 − 571 =
36. 36.862 − 354 =
37. 37.424 − 149 =
38. 38.398 + 394 =
39. 39.622 − 222 =
40. 40.674 + 533 =

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