3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 780 · 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. 1.422 + 121 =
2. 2.245 + 235 =
3. 3.636 + 552 =
4. 4.453 − 202 =
5. 5.427 − 151 =
6. 6.725 − 296 =
7. 7.279 + 595 =
8. 8.637 + 398 =
9. 9.413 − 124 =
10. 10.852 − 369 =
11. 11.168 + 172 =
12. 12.599 − 363 =
13. 13.754 − 221 =
14. 14.347 + 447 =
15. 15.444 + 214 =
16. 16.560 − 441 =
17. 17.447 − 181 =
18. 18.802 − 151 =
19. 19.970 − 336 =
20. 20.128 + 448 =
21. 21.710 − 325 =
22. 22.625 − 411 =
23. 23.285 + 321 =
24. 24.874 − 484 =
25. 25.862 − 384 =
26. 26.660 + 531 =
27. 27.544 + 224 =
28. 28.687 + 688 =
29. 29.938 − 469 =
30. 30.357 + 342 =
31. 31.804 − 531 =
32. 32.639 + 478 =
33. 33.501 + 361 =
34. 34.343 + 441 =
35. 35.426 − 266 =
36. 36.451 − 115 =
37. 37.897 − 158 =
38. 38.490 + 153 =
39. 39.887 − 262 =
40. 40.482 + 573 =

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