3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 552 · 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. 1.158 + 249 =
2. 2.155 + 194 =
3. 3.487 − 262 =
4. 4.525 − 402 =
5. 5.645 + 512 =
6. 6.258 + 415 =
7. 7.655 − 434 =
8. 8.949 − 388 =
9. 9.496 + 139 =
10. 10.777 + 271 =
11. 11.794 − 455 =
12. 12.314 + 331 =
13. 13.986 − 309 =
14. 14.967 − 741 =
15. 15.572 − 119 =
16. 16.277 + 146 =
17. 17.584 − 352 =
18. 18.505 − 259 =
19. 19.646 − 247 =
20. 20.423 + 335 =
21. 21.758 − 371 =
22. 22.861 − 631 =
23. 23.224 + 404 =
24. 24.568 − 261 =
25. 25.450 − 217 =
26. 26.780 + 478 =
27. 27.630 − 382 =
28. 28.850 − 366 =
29. 29.439 + 501 =
30. 30.939 − 444 =
31. 31.604 − 141 =
32. 32.729 + 129 =
33. 33.826 − 151 =
34. 34.770 + 134 =
35. 35.679 + 411 =
36. 36.639 − 269 =
37. 37.436 + 155 =
38. 38.312 + 469 =
39. 39.426 + 334 =
40. 40.458 + 147 =

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