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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 718 · 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. 1.414 + 441 =
  2. 2.973 − 326 =
  3. 3.467 − 284 =
  4. 4.718 + 205 =
  5. 5.586 + 419 =
  6. 6.228 + 117 =
  7. 7.450 − 153 =
  8. 8.501 − 189 =
  9. 9.374 + 333 =
  10. 10.550 − 295 =
  11. 11.890 − 634 =
  12. 12.747 − 524 =
  13. 13.261 + 523 =
  14. 14.888 − 613 =
  15. 15.500 + 289 =
  16. 16.123 + 334 =
  17. 17.567 + 653 =
  18. 18.628 + 476 =
  19. 19.353 + 591 =
  20. 20.473 − 355 =
  21. 21.611 − 297 =
  22. 22.611 − 186 =
  23. 23.629 + 593 =
  24. 24.263 + 321 =
  25. 25.272 + 331 =
  26. 26.205 + 655 =
  27. 27.702 − 301 =
  28. 28.722 + 112 =
  29. 29.349 + 683 =
  30. 30.332 + 409 =
  31. 31.852 − 643 =
  32. 32.768 + 511 =
  33. 33.470 − 298 =
  34. 34.358 + 475 =
  35. 35.450 − 187 =
  36. 36.288 + 262 =
  37. 37.444 − 321 =
  38. 38.754 − 445 =
  39. 39.495 − 261 =
  40. 40.363 + 624 =

Answer key

  1. 855
  2. 647
  3. 183
  4. 923
  5. 1005
  6. 345
  7. 297
  8. 312
  9. 707
  10. 255
  11. 256
  12. 223
  13. 784
  14. 275
  15. 789
  16. 457
  17. 1220
  18. 1104
  19. 944
  20. 118
  21. 314
  22. 425
  23. 1222
  24. 584
  25. 603
  26. 860
  27. 401
  28. 834
  29. 1032
  30. 741
  31. 209
  32. 1279
  33. 172
  34. 833
  35. 263
  36. 550
  37. 123
  38. 309
  39. 234
  40. 987

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