3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 350 · 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. 1.438 − 238 =
2. 2.969 − 131 =
3. 3.871 − 314 =
4. 4.218 + 287 =
5. 5.591 − 235 =
6. 6.136 + 144 =
7. 7.872 − 385 =
8. 8.649 − 365 =
9. 9.765 + 442 =
10. 10.725 + 636 =
11. 11.538 − 355 =
12. 12.601 + 171 =
13. 13.650 − 475 =
14. 14.307 + 506 =
15. 15.751 + 303 =
16. 16.759 − 298 =
17. 17.766 + 471 =
18. 18.518 − 191 =
19. 19.276 + 213 =
20. 20.948 − 691 =
21. 21.451 − 212 =
22. 22.636 + 606 =
23. 23.475 + 204 =
24. 24.662 − 332 =
25. 25.572 + 355 =
26. 26.289 + 338 =
27. 27.600 − 389 =
28. 28.473 + 594 =
29. 29.373 + 541 =
30. 30.619 − 431 =
31. 31.441 + 242 =
32. 32.803 − 125 =
33. 33.651 − 217 =
34. 34.261 + 508 =
35. 35.718 + 151 =
36. 36.590 − 354 =
37. 37.518 + 445 =
38. 38.461 − 342 =
39. 39.421 + 635 =
40. 40.870 − 477 =

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