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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 442 · 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. 1.568 − 309 =
  2. 2.751 + 667 =
  3. 3.289 + 361 =
  4. 4.528 − 117 =
  5. 5.611 + 142 =
  6. 6.857 − 636 =
  7. 7.506 − 386 =
  8. 8.617 − 126 =
  9. 9.674 − 504 =
  10. 10.133 + 383 =
  11. 11.940 − 798 =
  12. 12.609 + 318 =
  13. 13.589 + 389 =
  14. 14.282 + 249 =
  15. 15.637 + 209 =
  16. 16.677 + 329 =
  17. 17.488 − 142 =
  18. 18.296 + 476 =
  19. 19.343 + 315 =
  20. 20.530 − 409 =
  21. 21.579 − 311 =
  22. 22.162 + 564 =
  23. 23.490 + 159 =
  24. 24.496 − 144 =
  25. 25.645 + 601 =
  26. 26.718 + 469 =
  27. 27.837 − 135 =
  28. 28.920 − 812 =
  29. 29.533 − 284 =
  30. 30.891 − 329 =
  31. 31.215 + 448 =
  32. 32.804 − 411 =
  33. 33.826 − 361 =
  34. 34.684 + 132 =
  35. 35.446 − 319 =
  36. 36.302 + 152 =
  37. 37.174 + 428 =
  38. 38.191 + 217 =
  39. 39.232 + 551 =
  40. 40.556 − 351 =

Answer key

  1. 259
  2. 1418
  3. 650
  4. 411
  5. 753
  6. 221
  7. 120
  8. 491
  9. 170
  10. 516
  11. 142
  12. 927
  13. 978
  14. 531
  15. 846
  16. 1006
  17. 346
  18. 772
  19. 658
  20. 121
  21. 268
  22. 726
  23. 649
  24. 352
  25. 1246
  26. 1187
  27. 702
  28. 108
  29. 249
  30. 562
  31. 663
  32. 393
  33. 465
  34. 816
  35. 127
  36. 454
  37. 602
  38. 408
  39. 783
  40. 205

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