3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 985 · 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. 1.229 + 527 =
2. 2.489 + 288 =
3. 3.125 + 446 =
4. 4.464 + 431 =
5. 5.617 − 179 =
6. 6.381 + 501 =
7. 7.578 + 567 =
8. 8.196 + 205 =
9. 9.145 + 219 =
10. 10.733 − 626 =
11. 11.161 + 566 =
12. 12.128 + 356 =
13. 13.742 − 388 =
14. 14.566 − 397 =
15. 15.455 − 224 =
16. 16.443 − 336 =
17. 17.746 + 501 =
18. 18.258 + 181 =
19. 19.354 + 183 =
20. 20.493 − 311 =
21. 21.511 + 635 =
22. 22.545 − 321 =
23. 23.475 − 338 =
24. 24.479 − 183 =
25. 25.153 + 638 =
26. 26.508 − 181 =
27. 27.922 − 122 =
28. 28.387 + 142 =
29. 29.142 + 362 =
30. 30.571 − 156 =
31. 31.551 + 273 =
32. 32.617 + 666 =
33. 33.482 − 309 =
34. 34.328 + 382 =
35. 35.689 + 417 =
36. 36.792 − 692 =
37. 37.534 − 261 =
38. 38.944 − 444 =
39. 39.287 + 624 =
40. 40.721 + 631 =

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