3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 34 · 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. 1.242 + 533 =
2. 2.266 + 471 =
3. 3.471 − 187 =
4. 4.814 − 648 =
5. 5.637 + 245 =
6. 6.731 + 193 =
7. 7.140 + 233 =
8. 8.695 − 453 =
9. 9.900 − 739 =
10. 10.970 − 253 =
11. 11.445 − 143 =
12. 12.881 − 352 =
13. 13.945 − 716 =
14. 14.956 − 405 =
15. 15.730 + 638 =
16. 16.582 − 407 =
17. 17.544 + 526 =
18. 18.270 + 609 =
19. 19.494 + 274 =
20. 20.768 − 146 =
21. 21.697 + 373 =
22. 22.281 + 489 =
23. 23.450 − 201 =
24. 24.601 − 331 =
25. 25.443 − 316 =
26. 26.238 + 401 =
27. 27.686 − 216 =
28. 28.625 − 183 =
29. 29.490 + 387 =
30. 30.498 + 687 =
31. 31.471 − 345 =
32. 32.265 + 418 =
33. 33.568 + 582 =
34. 34.750 + 515 =
35. 35.287 + 607 =
36. 36.772 + 331 =
37. 37.687 + 319 =
38. 38.865 − 605 =
39. 39.673 − 541 =
40. 40.667 − 171 =

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