3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 189 · 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. 1.500 + 365 =
2. 2.580 + 196 =
3. 3.887 − 173 =
4. 4.280 + 156 =
5. 5.140 + 357 =
6. 6.907 − 195 =
7. 7.521 − 261 =
8. 8.442 − 145 =
9. 9.821 − 308 =
10. 10.358 + 128 =
11. 11.958 − 421 =
12. 12.416 + 266 =
13. 13.397 + 136 =
14. 14.501 + 587 =
15. 15.139 + 367 =
16. 16.508 − 394 =
17. 17.753 − 558 =
18. 18.319 + 165 =
19. 19.700 − 185 =
20. 20.201 + 171 =
21. 21.217 + 345 =
22. 22.595 + 623 =
23. 23.607 + 349 =
24. 24.585 + 531 =
25. 25.719 − 185 =
26. 26.946 − 321 =
27. 27.752 + 287 =
28. 28.759 + 592 =
29. 29.171 + 445 =
30. 30.412 − 302 =
31. 31.959 − 822 =
32. 32.324 + 446 =
33. 33.857 − 714 =
34. 34.286 + 201 =
35. 35.160 + 124 =
36. 36.753 − 535 =
37. 37.254 + 251 =
38. 38.294 + 231 =
39. 39.435 − 309 =
40. 40.694 + 325 =

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