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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 499 · 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. 1.862 − 276 =
  2. 2.159 + 347 =
  3. 3.430 + 285 =
  4. 4.463 − 124 =
  5. 5.241 + 566 =
  6. 6.847 − 534 =
  7. 7.227 + 181 =
  8. 8.459 + 151 =
  9. 9.461 + 365 =
  10. 10.517 − 261 =
  11. 11.187 + 672 =
  12. 12.531 − 366 =
  13. 13.194 + 144 =
  14. 14.229 + 413 =
  15. 15.472 + 401 =
  16. 16.708 + 397 =
  17. 17.168 + 676 =
  18. 18.209 + 511 =
  19. 19.878 − 189 =
  20. 20.784 + 427 =
  21. 21.406 + 509 =
  22. 22.801 − 457 =
  23. 23.576 − 445 =
  24. 24.628 + 244 =
  25. 25.464 − 169 =
  26. 26.808 − 136 =
  27. 27.318 + 298 =
  28. 28.809 − 418 =
  29. 29.787 + 648 =
  30. 30.154 + 401 =
  31. 31.629 − 525 =
  32. 32.560 − 141 =
  33. 33.472 − 205 =
  34. 34.469 + 143 =
  35. 35.859 − 666 =
  36. 36.778 − 341 =
  37. 37.306 + 637 =
  38. 38.284 + 601 =
  39. 39.544 + 632 =
  40. 40.506 − 126 =

Answer key

  1. 586
  2. 506
  3. 715
  4. 339
  5. 807
  6. 313
  7. 408
  8. 610
  9. 826
  10. 256
  11. 859
  12. 165
  13. 338
  14. 642
  15. 873
  16. 1105
  17. 844
  18. 720
  19. 689
  20. 1211
  21. 915
  22. 344
  23. 131
  24. 872
  25. 295
  26. 672
  27. 616
  28. 391
  29. 1435
  30. 555
  31. 104
  32. 419
  33. 267
  34. 612
  35. 193
  36. 437
  37. 943
  38. 885
  39. 1176
  40. 380

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