3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 170 · 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. 1.485 − 195 =
2. 2.247 + 332 =
3. 3.455 − 327 =
4. 4.857 − 598 =
5. 5.422 − 128 =
6. 6.555 − 139 =
7. 7.226 + 484 =
8. 8.985 − 357 =
9. 9.545 − 176 =
10. 10.887 − 413 =
11. 11.577 − 343 =
12. 12.335 + 442 =
13. 13.427 − 274 =
14. 14.337 + 279 =
15. 15.347 + 382 =
16. 16.754 − 606 =
17. 17.148 + 265 =
18. 18.335 + 433 =
19. 19.267 + 241 =
20. 20.490 + 581 =
21. 21.392 + 634 =
22. 22.732 − 384 =
23. 23.729 + 558 =
24. 24.660 − 123 =
25. 25.768 − 663 =
26. 26.870 − 124 =
27. 27.528 − 298 =
28. 28.832 − 356 =
29. 29.577 + 187 =
30. 30.425 + 482 =
31. 31.139 + 134 =
32. 32.451 − 291 =
33. 33.537 − 435 =
34. 34.132 + 655 =
35. 35.439 − 198 =
36. 36.568 − 201 =
37. 37.454 + 184 =
38. 38.697 + 126 =
39. 39.748 − 427 =
40. 40.279 + 521 =

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