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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 55 · 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. 1.305 + 573 =
  2. 2.662 − 117 =
  3. 3.437 + 245 =
  4. 4.550 − 253 =
  5. 5.574 + 658 =
  6. 6.242 + 146 =
  7. 7.512 + 649 =
  8. 8.410 + 165 =
  9. 9.869 − 481 =
  10. 10.761 + 654 =
  11. 11.821 − 716 =
  12. 12.422 + 599 =
  13. 13.234 + 497 =
  14. 14.128 + 383 =
  15. 15.181 + 138 =
  16. 16.809 − 495 =
  17. 17.989 − 541 =
  18. 18.305 + 191 =
  19. 19.195 + 462 =
  20. 20.236 + 371 =
  21. 21.617 + 182 =
  22. 22.822 − 266 =
  23. 23.516 + 446 =
  24. 24.814 − 308 =
  25. 25.552 + 559 =
  26. 26.507 + 251 =
  27. 27.471 − 216 =
  28. 28.353 + 323 =
  29. 29.475 − 308 =
  30. 30.890 − 754 =
  31. 31.930 − 484 =
  32. 32.224 + 122 =
  33. 33.570 + 501 =
  34. 34.513 − 194 =
  35. 35.735 − 426 =
  36. 36.708 + 197 =
  37. 37.911 − 415 =
  38. 38.446 + 215 =
  39. 39.517 + 193 =
  40. 40.727 − 525 =

Answer key

  1. 878
  2. 545
  3. 682
  4. 297
  5. 1232
  6. 388
  7. 1161
  8. 575
  9. 388
  10. 1415
  11. 105
  12. 1021
  13. 731
  14. 511
  15. 319
  16. 314
  17. 448
  18. 496
  19. 657
  20. 607
  21. 799
  22. 556
  23. 962
  24. 506
  25. 1111
  26. 758
  27. 255
  28. 676
  29. 167
  30. 136
  31. 446
  32. 346
  33. 1071
  34. 319
  35. 309
  36. 905
  37. 496
  38. 661
  39. 710
  40. 202

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