3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 411 · 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. 1.567 + 591 =
2. 2.815 − 551 =
3. 3.936 − 377 =
4. 4.689 − 581 =
5. 5.768 + 359 =
6. 6.180 + 443 =
7. 7.534 − 148 =
8. 8.585 − 447 =
9. 9.517 − 149 =
10. 10.292 + 298 =
11. 11.533 − 221 =
12. 12.184 + 664 =
13. 13.190 + 479 =
14. 14.672 − 158 =
15. 15.466 − 265 =
16. 16.627 + 513 =
17. 17.521 + 406 =
18. 18.685 − 482 =
19. 19.871 − 665 =
20. 20.244 + 544 =
21. 21.561 − 276 =
22. 22.906 − 344 =
23. 23.773 − 207 =
24. 24.248 + 365 =
25. 25.148 + 114 =
26. 26.424 + 545 =
27. 27.569 − 253 =
28. 28.637 − 338 =
29. 29.611 − 426 =
30. 30.249 + 642 =
31. 31.384 + 255 =
32. 32.403 + 268 =
33. 33.704 − 195 =
34. 34.524 + 144 =
35. 35.535 − 366 =
36. 36.431 − 219 =
37. 37.827 − 587 =
38. 38.978 − 795 =
39. 39.195 + 124 =
40. 40.671 − 367 =

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