3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 223 · 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. 1.866 − 486 =
2. 2.910 − 127 =
3. 3.730 − 363 =
4. 4.548 − 166 =
5. 5.797 − 381 =
6. 6.157 + 135 =
7. 7.639 − 253 =
8. 8.715 − 511 =
9. 9.310 + 524 =
10. 10.199 + 685 =
11. 11.917 − 347 =
12. 12.393 + 245 =
13. 13.492 − 271 =
14. 14.725 + 608 =
15. 15.282 + 387 =
16. 16.478 − 205 =
17. 17.700 + 238 =
18. 18.606 − 468 =
19. 19.978 − 434 =
20. 20.818 − 361 =
21. 21.648 − 244 =
22. 22.474 − 312 =
23. 23.197 + 552 =
24. 24.421 − 158 =
25. 25.697 − 498 =
26. 26.447 − 208 =
27. 27.470 + 404 =
28. 28.197 + 395 =
29. 29.359 + 372 =
30. 30.727 − 316 =
31. 31.338 + 195 =
32. 32.248 + 681 =
33. 33.737 − 627 =
34. 34.979 − 627 =
35. 35.512 − 285 =
36. 36.658 − 369 =
37. 37.275 + 431 =
38. 38.198 + 391 =
39. 39.591 + 131 =
40. 40.761 + 169 =

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