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3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 754 · 40 questions
TalentJR

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.

NameDateTime takenScore ___ / 40
  1. 1.474 − 229 =
  2. 2.412 − 161 =
  3. 3.528 − 119 =
  4. 4.910 − 501 =
  5. 5.757 − 119 =
  6. 6.715 + 358 =
  7. 7.906 − 681 =
  8. 8.338 + 198 =
  9. 9.150 + 192 =
  10. 10.555 + 436 =
  11. 11.419 + 294 =
  12. 12.659 − 344 =
  13. 13.548 + 682 =
  14. 14.178 + 125 =
  15. 15.716 + 656 =
  16. 16.495 − 389 =
  17. 17.444 + 667 =
  18. 18.534 − 253 =
  19. 19.458 − 304 =
  20. 20.628 + 643 =
  21. 21.429 + 509 =
  22. 22.266 + 121 =
  23. 23.836 − 262 =
  24. 24.736 + 211 =
  25. 25.760 + 148 =
  26. 26.776 + 158 =
  27. 27.771 − 539 =
  28. 28.396 + 332 =
  29. 29.205 + 672 =
  30. 30.254 + 523 =
  31. 31.494 − 201 =
  32. 32.733 − 559 =
  33. 33.248 + 275 =
  34. 34.538 + 315 =
  35. 35.619 − 118 =
  36. 36.437 + 431 =
  37. 37.753 − 231 =
  38. 38.673 − 431 =
  39. 39.469 + 526 =
  40. 40.390 + 278 =

Answer key

  1. 245
  2. 251
  3. 409
  4. 409
  5. 638
  6. 1073
  7. 225
  8. 536
  9. 342
  10. 991
  11. 713
  12. 315
  13. 1230
  14. 303
  15. 1372
  16. 106
  17. 1111
  18. 281
  19. 154
  20. 1271
  21. 938
  22. 387
  23. 574
  24. 947
  25. 908
  26. 934
  27. 232
  28. 728
  29. 877
  30. 777
  31. 293
  32. 174
  33. 523
  34. 853
  35. 501
  36. 868
  37. 522
  38. 242
  39. 995
  40. 668

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