3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 801 · 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. 1.745 − 444 =
2. 2.513 + 303 =
3. 3.389 + 314 =
4. 4.330 + 613 =
5. 5.640 + 621 =
6. 6.327 + 191 =
7. 7.440 − 206 =
8. 8.479 − 311 =
9. 9.589 + 669 =
10. 10.939 − 166 =
11. 11.696 − 242 =
12. 12.234 + 165 =
13. 13.639 + 539 =
14. 14.505 − 398 =
15. 15.228 + 686 =
16. 16.166 + 139 =
17. 17.472 − 275 =
18. 18.513 − 398 =
19. 19.495 − 134 =
20. 20.798 − 372 =
21. 21.649 + 455 =
22. 22.599 − 471 =
23. 23.669 + 572 =
24. 24.896 − 176 =
25. 25.530 + 248 =
26. 26.826 − 463 =
27. 27.945 − 794 =
28. 28.253 + 251 =
29. 29.725 + 453 =
30. 30.532 − 266 =
31. 31.657 + 614 =
32. 32.853 − 164 =
33. 33.622 + 312 =
34. 34.356 + 171 =
35. 35.541 − 363 =
36. 36.820 − 158 =
37. 37.500 − 201 =
38. 38.947 − 588 =
39. 39.528 − 371 =
40. 40.708 − 171 =

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