3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 633 · 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. 1.689 − 136 =
2. 2.329 + 228 =
3. 3.594 + 441 =
4. 4.546 − 257 =
5. 5.646 + 152 =
6. 6.412 − 297 =
7. 7.627 − 207 =
8. 8.590 − 468 =
9. 9.495 − 156 =
10. 10.163 + 145 =
11. 11.418 − 151 =
12. 12.917 − 258 =
13. 13.789 + 462 =
14. 14.197 + 131 =
15. 15.835 − 532 =
16. 16.644 − 519 =
17. 17.369 + 171 =
18. 18.399 + 329 =
19. 19.906 − 366 =
20. 20.667 − 331 =
21. 21.835 − 219 =
22. 22.231 + 221 =
23. 23.243 + 194 =
24. 24.718 − 454 =
25. 25.801 − 121 =
26. 26.762 + 529 =
27. 27.950 − 121 =
28. 28.438 + 146 =
29. 29.516 + 378 =
30. 30.558 − 447 =
31. 31.555 + 463 =
32. 32.499 − 251 =
33. 33.655 + 221 =
34. 34.773 − 322 =
35. 35.185 + 661 =
36. 36.710 − 414 =
37. 37.127 + 236 =
38. 38.705 + 521 =
39. 39.541 − 263 =
40. 40.798 − 528 =

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