3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 960 · 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. 1.221 + 342 =
2. 2.725 + 201 =
3. 3.735 + 325 =
4. 4.629 − 211 =
5. 5.257 + 491 =
6. 6.258 + 687 =
7. 7.263 + 378 =
8. 8.698 − 492 =
9. 9.173 + 126 =
10. 10.913 − 573 =
11. 11.548 + 475 =
12. 12.605 − 218 =
13. 13.365 + 254 =
14. 14.901 − 732 =
15. 15.223 + 152 =
16. 16.723 − 114 =
17. 17.457 + 577 =
18. 18.775 − 441 =
19. 19.975 − 718 =
20. 20.566 − 328 =
21. 21.624 − 131 =
22. 22.555 − 451 =
23. 23.238 + 419 =
24. 24.984 − 722 =
25. 25.711 + 134 =
26. 26.423 + 166 =
27. 27.239 + 357 =
28. 28.893 − 592 =
29. 29.417 + 144 =
30. 30.308 + 364 =
31. 31.544 − 341 =
32. 32.732 − 521 =
33. 33.514 − 276 =
34. 34.798 − 327 =
35. 35.479 − 124 =
36. 36.480 − 119 =
37. 37.343 + 112 =
38. 38.150 + 119 =
39. 39.517 − 175 =
40. 40.931 − 397 =

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