3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 133 · 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. 1.214 + 113 =
2. 2.767 + 209 =
3. 3.179 + 377 =
4. 4.227 + 474 =
5. 5.481 + 194 =
6. 6.456 + 437 =
7. 7.760 − 165 =
8. 8.304 + 611 =
9. 9.421 + 478 =
10. 10.923 − 342 =
11. 11.596 − 357 =
12. 12.985 − 262 =
13. 13.443 + 671 =
14. 14.659 + 233 =
15. 15.715 + 275 =
16. 16.533 − 419 =
17. 17.293 + 154 =
18. 18.520 + 352 =
19. 19.951 − 588 =
20. 20.920 − 277 =
21. 21.433 − 155 =
22. 22.445 + 151 =
23. 23.193 + 272 =
24. 24.515 + 645 =
25. 25.887 − 412 =
26. 26.463 − 125 =
27. 27.628 − 141 =
28. 28.775 − 325 =
29. 29.673 + 578 =
30. 30.841 − 174 =
31. 31.796 − 316 =
32. 32.940 − 581 =
33. 33.764 − 339 =
34. 34.635 − 231 =
35. 35.650 + 195 =
36. 36.643 − 486 =
37. 37.853 − 237 =
38. 38.283 + 544 =
39. 39.558 − 333 =
40. 40.130 + 558 =

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