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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 148 · 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. 1.214 + 247 =
  2. 2.417 + 457 =
  3. 3.703 + 142 =
  4. 4.733 + 648 =
  5. 5.751 + 581 =
  6. 6.301 + 448 =
  7. 7.299 + 237 =
  8. 8.460 + 158 =
  9. 9.658 − 228 =
  10. 10.477 − 151 =
  11. 11.256 + 221 =
  12. 12.504 + 628 =
  13. 13.438 − 234 =
  14. 14.819 − 587 =
  15. 15.481 + 144 =
  16. 16.454 − 296 =
  17. 17.707 + 397 =
  18. 18.518 − 201 =
  19. 19.481 + 689 =
  20. 20.929 − 331 =
  21. 21.783 + 474 =
  22. 22.452 + 153 =
  23. 23.707 + 255 =
  24. 24.149 + 387 =
  25. 25.522 + 176 =
  26. 26.977 − 418 =
  27. 27.837 − 676 =
  28. 28.451 − 158 =
  29. 29.479 − 148 =
  30. 30.238 + 286 =
  31. 31.640 − 339 =
  32. 32.908 − 131 =
  33. 33.205 + 463 =
  34. 34.190 + 202 =
  35. 35.608 − 124 =
  36. 36.907 − 368 =
  37. 37.461 + 176 =
  38. 38.735 − 146 =
  39. 39.127 + 508 =
  40. 40.609 + 523 =

Answer key

  1. 461
  2. 874
  3. 845
  4. 1381
  5. 1332
  6. 749
  7. 536
  8. 618
  9. 430
  10. 326
  11. 477
  12. 1132
  13. 204
  14. 232
  15. 625
  16. 158
  17. 1104
  18. 317
  19. 1170
  20. 598
  21. 1257
  22. 605
  23. 962
  24. 536
  25. 698
  26. 559
  27. 161
  28. 293
  29. 331
  30. 524
  31. 301
  32. 777
  33. 668
  34. 392
  35. 484
  36. 539
  37. 637
  38. 589
  39. 635
  40. 1132

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