3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 361 · 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. 1.127 + 409 =
2. 2.615 − 456 =
3. 3.733 − 477 =
4. 4.850 − 122 =
5. 5.300 + 232 =
6. 6.213 + 408 =
7. 7.849 − 417 =
8. 8.469 + 534 =
9. 9.475 + 657 =
10. 10.559 − 204 =
11. 11.459 + 115 =
12. 12.675 + 616 =
13. 13.650 − 163 =
14. 14.661 + 685 =
15. 15.794 − 534 =
16. 16.166 + 545 =
17. 17.499 + 378 =
18. 18.810 − 169 =
19. 19.522 − 248 =
20. 20.447 − 293 =
21. 21.845 − 311 =
22. 22.532 − 281 =
23. 23.504 − 305 =
24. 24.463 + 685 =
25. 25.397 + 404 =
26. 26.613 + 676 =
27. 27.528 − 151 =
28. 28.541 + 307 =
29. 29.656 + 628 =
30. 30.312 + 224 =
31. 31.581 + 114 =
32. 32.542 − 143 =
33. 33.511 − 217 =
34. 34.787 − 476 =
35. 35.478 − 308 =
36. 36.739 − 396 =
37. 37.561 + 173 =
38. 38.673 + 478 =
39. 39.931 − 573 =
40. 40.910 − 372 =

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