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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 103 · 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. 1.246 + 411 =
  2. 2.296 + 607 =
  3. 3.661 + 684 =
  4. 4.767 − 511 =
  5. 5.559 + 453 =
  6. 6.829 − 179 =
  7. 7.402 + 193 =
  8. 8.441 + 579 =
  9. 9.728 + 182 =
  10. 10.309 + 249 =
  11. 11.159 + 172 =
  12. 12.642 − 511 =
  13. 13.429 − 302 =
  14. 14.700 + 244 =
  15. 15.160 + 149 =
  16. 16.903 − 424 =
  17. 17.802 − 254 =
  18. 18.306 + 565 =
  19. 19.486 + 195 =
  20. 20.601 − 208 =
  21. 21.817 − 342 =
  22. 22.683 − 132 =
  23. 23.956 − 187 =
  24. 24.459 + 131 =
  25. 25.521 + 359 =
  26. 26.688 − 141 =
  27. 27.502 − 277 =
  28. 28.330 + 327 =
  29. 29.562 − 146 =
  30. 30.348 + 201 =
  31. 31.512 + 682 =
  32. 32.445 − 205 =
  33. 33.977 − 245 =
  34. 34.149 + 574 =
  35. 35.898 − 778 =
  36. 36.784 + 607 =
  37. 37.144 + 311 =
  38. 38.523 − 207 =
  39. 39.607 − 376 =
  40. 40.501 − 242 =

Answer key

  1. 657
  2. 903
  3. 1345
  4. 256
  5. 1012
  6. 650
  7. 595
  8. 1020
  9. 910
  10. 558
  11. 331
  12. 131
  13. 127
  14. 944
  15. 309
  16. 479
  17. 548
  18. 871
  19. 681
  20. 393
  21. 475
  22. 551
  23. 769
  24. 590
  25. 880
  26. 547
  27. 225
  28. 657
  29. 416
  30. 549
  31. 1194
  32. 240
  33. 732
  34. 723
  35. 120
  36. 1391
  37. 455
  38. 316
  39. 231
  40. 259

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