3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 659 · 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. 1.612 + 345 =
2. 2.932 − 151 =
3. 3.274 + 479 =
4. 4.200 + 216 =
5. 5.574 + 173 =
6. 6.400 + 629 =
7. 7.956 − 604 =
8. 8.745 − 128 =
9. 9.463 + 573 =
10. 10.880 − 635 =
11. 11.404 + 461 =
12. 12.923 − 608 =
13. 13.974 − 581 =
14. 14.893 − 268 =
15. 15.855 − 262 =
16. 16.768 + 492 =
17. 17.430 − 136 =
18. 18.821 − 481 =
19. 19.716 − 301 =
20. 20.211 + 164 =
21. 21.586 − 211 =
22. 22.462 + 388 =
23. 23.700 + 671 =
24. 24.460 + 176 =
25. 25.473 − 187 =
26. 26.158 + 511 =
27. 27.566 + 245 =
28. 28.740 + 524 =
29. 29.632 − 431 =
30. 30.965 − 212 =
31. 31.605 + 336 =
32. 32.591 − 169 =
33. 33.162 + 251 =
34. 34.852 − 362 =
35. 35.251 + 138 =
36. 36.670 − 537 =
37. 37.834 − 591 =
38. 38.460 + 465 =
39. 39.771 + 355 =
40. 40.572 − 193 =

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