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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 755 · 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. 1.689 + 475 =
  2. 2.728 − 291 =
  3. 3.497 + 601 =
  4. 4.669 + 573 =
  5. 5.811 − 141 =
  6. 6.875 − 396 =
  7. 7.503 − 169 =
  8. 8.508 − 406 =
  9. 9.496 − 394 =
  10. 10.465 − 162 =
  11. 11.696 − 484 =
  12. 12.971 − 218 =
  13. 13.651 − 241 =
  14. 14.515 − 179 =
  15. 15.564 + 601 =
  16. 16.450 + 675 =
  17. 17.446 + 329 =
  18. 18.272 + 235 =
  19. 19.759 − 309 =
  20. 20.463 − 301 =
  21. 21.445 − 272 =
  22. 22.265 + 676 =
  23. 23.454 − 226 =
  24. 24.274 + 667 =
  25. 25.492 − 148 =
  26. 26.331 + 187 =
  27. 27.661 − 168 =
  28. 28.628 − 233 =
  29. 29.847 − 583 =
  30. 30.735 + 274 =
  31. 31.428 + 621 =
  32. 32.489 − 247 =
  33. 33.264 + 161 =
  34. 34.784 − 546 =
  35. 35.164 + 227 =
  36. 36.679 − 566 =
  37. 37.742 + 445 =
  38. 38.454 − 193 =
  39. 39.537 + 211 =
  40. 40.244 + 552 =

Answer key

  1. 1164
  2. 437
  3. 1098
  4. 1242
  5. 670
  6. 479
  7. 334
  8. 102
  9. 102
  10. 303
  11. 212
  12. 753
  13. 410
  14. 336
  15. 1165
  16. 1125
  17. 775
  18. 507
  19. 450
  20. 162
  21. 173
  22. 941
  23. 228
  24. 941
  25. 344
  26. 518
  27. 493
  28. 395
  29. 264
  30. 1009
  31. 1049
  32. 242
  33. 425
  34. 238
  35. 391
  36. 113
  37. 1187
  38. 261
  39. 748
  40. 796

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