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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 50 · 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. 1.522 + 145 =
  2. 2.477 − 239 =
  3. 3.514 − 118 =
  4. 4.630 + 546 =
  5. 5.130 + 311 =
  6. 6.716 − 235 =
  7. 7.246 + 594 =
  8. 8.815 − 215 =
  9. 9.205 + 662 =
  10. 10.505 − 393 =
  11. 11.517 − 148 =
  12. 12.459 + 673 =
  13. 13.459 − 129 =
  14. 14.616 − 231 =
  15. 15.715 + 175 =
  16. 16.274 + 176 =
  17. 17.605 − 197 =
  18. 18.486 + 484 =
  19. 19.395 + 299 =
  20. 20.814 − 464 =
  21. 21.374 + 157 =
  22. 22.512 − 159 =
  23. 23.427 + 227 =
  24. 24.255 + 291 =
  25. 25.613 − 429 =
  26. 26.933 − 303 =
  27. 27.612 + 265 =
  28. 28.320 + 418 =
  29. 29.265 + 496 =
  30. 30.531 + 233 =
  31. 31.627 + 128 =
  32. 32.678 − 306 =
  33. 33.415 − 185 =
  34. 34.730 − 247 =
  35. 35.676 − 229 =
  36. 36.923 − 689 =
  37. 37.919 − 589 =
  38. 38.765 + 138 =
  39. 39.178 + 133 =
  40. 40.859 − 474 =

Answer key

  1. 667
  2. 238
  3. 396
  4. 1176
  5. 441
  6. 481
  7. 840
  8. 600
  9. 867
  10. 112
  11. 369
  12. 1132
  13. 330
  14. 385
  15. 890
  16. 450
  17. 408
  18. 970
  19. 694
  20. 350
  21. 531
  22. 353
  23. 654
  24. 546
  25. 184
  26. 630
  27. 877
  28. 738
  29. 761
  30. 764
  31. 755
  32. 372
  33. 230
  34. 483
  35. 447
  36. 234
  37. 330
  38. 903
  39. 311
  40. 385

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