3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 605 · 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. 1.688 + 193 =
2. 2.657 + 181 =
3. 3.680 + 503 =
4. 4.820 − 184 =
5. 5.402 + 636 =
6. 6.646 − 176 =
7. 7.502 − 336 =
8. 8.474 − 191 =
9. 9.199 + 129 =
10. 10.523 − 333 =
11. 11.418 − 139 =
12. 12.603 + 402 =
13. 13.274 + 598 =
14. 14.978 − 221 =
15. 15.929 − 759 =
16. 16.652 + 225 =
17. 17.579 + 601 =
18. 18.161 + 252 =
19. 19.755 + 462 =
20. 20.217 + 625 =
21. 21.967 − 241 =
22. 22.733 − 229 =
23. 23.716 − 421 =
24. 24.955 − 514 =
25. 25.939 − 351 =
26. 26.832 − 484 =
27. 27.659 − 161 =
28. 28.569 + 458 =
29. 29.420 − 119 =
30. 30.489 − 223 =
31. 31.369 + 203 =
32. 32.775 − 308 =
33. 33.518 + 461 =
34. 34.556 − 292 =
35. 35.770 − 524 =
36. 36.911 − 611 =
37. 37.498 + 237 =
38. 38.241 + 355 =
39. 39.298 + 401 =
40. 40.685 − 341 =

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