3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 703 · 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. 1.507 + 184 =
2. 2.540 − 331 =
3. 3.138 + 689 =
4. 4.259 + 278 =
5. 5.801 − 201 =
6. 6.771 − 454 =
7. 7.785 − 553 =
8. 8.506 − 184 =
9. 9.422 + 295 =
10. 10.159 + 355 =
11. 11.459 − 218 =
12. 12.613 − 357 =
13. 13.559 − 302 =
14. 14.767 − 135 =
15. 15.427 − 158 =
16. 16.741 − 177 =
17. 17.680 − 562 =
18. 18.669 − 535 =
19. 19.147 + 384 =
20. 20.194 + 192 =
21. 21.629 − 511 =
22. 22.429 − 313 =
23. 23.549 − 172 =
24. 24.928 − 141 =
25. 25.267 + 671 =
26. 26.171 + 466 =
27. 27.933 − 581 =
28. 28.667 − 121 =
29. 29.155 + 411 =
30. 30.632 + 259 =
31. 31.356 + 242 =
32. 32.740 + 146 =
33. 33.706 − 399 =
34. 34.540 + 516 =
35. 35.592 + 363 =
36. 36.680 + 678 =
37. 37.752 + 374 =
38. 38.433 − 251 =
39. 39.341 + 175 =
40. 40.274 + 506 =

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