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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 393 · 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. 1.140 + 393 =
  2. 2.746 − 302 =
  3. 3.247 + 566 =
  4. 4.454 + 124 =
  5. 5.708 + 602 =
  6. 6.689 + 551 =
  7. 7.584 + 444 =
  8. 8.846 − 631 =
  9. 9.528 + 251 =
  10. 10.934 − 787 =
  11. 11.189 + 332 =
  12. 12.943 − 362 =
  13. 13.630 + 117 =
  14. 14.703 − 453 =
  15. 15.791 − 232 =
  16. 16.581 − 239 =
  17. 17.256 + 169 =
  18. 18.629 + 502 =
  19. 19.145 + 426 =
  20. 20.436 + 189 =
  21. 21.452 + 261 =
  22. 22.357 + 341 =
  23. 23.848 − 633 =
  24. 24.673 + 389 =
  25. 25.764 + 629 =
  26. 26.510 + 561 =
  27. 27.417 + 479 =
  28. 28.220 + 152 =
  29. 29.624 + 227 =
  30. 30.469 + 402 =
  31. 31.734 + 558 =
  32. 32.397 + 231 =
  33. 33.519 − 132 =
  34. 34.349 + 411 =
  35. 35.203 + 246 =
  36. 36.439 + 191 =
  37. 37.812 − 114 =
  38. 38.554 + 321 =
  39. 39.129 + 224 =
  40. 40.723 + 544 =

Answer key

  1. 533
  2. 444
  3. 813
  4. 578
  5. 1310
  6. 1240
  7. 1028
  8. 215
  9. 779
  10. 147
  11. 521
  12. 581
  13. 747
  14. 250
  15. 559
  16. 342
  17. 425
  18. 1131
  19. 571
  20. 625
  21. 713
  22. 698
  23. 215
  24. 1062
  25. 1393
  26. 1071
  27. 896
  28. 372
  29. 851
  30. 871
  31. 1292
  32. 628
  33. 387
  34. 760
  35. 449
  36. 630
  37. 698
  38. 875
  39. 353
  40. 1267

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