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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 802 · 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. 1.589 + 131 =
  2. 2.886 − 415 =
  3. 3.708 − 331 =
  4. 4.875 − 262 =
  5. 5.499 + 121 =
  6. 6.506 + 571 =
  7. 7.585 − 148 =
  8. 8.707 + 156 =
  9. 9.131 + 641 =
  10. 10.138 + 407 =
  11. 11.244 + 661 =
  12. 12.378 + 494 =
  13. 13.634 + 561 =
  14. 14.449 + 182 =
  15. 15.644 + 666 =
  16. 16.353 + 516 =
  17. 17.447 − 312 =
  18. 18.422 + 298 =
  19. 19.680 + 431 =
  20. 20.174 + 211 =
  21. 21.540 − 176 =
  22. 22.799 − 263 =
  23. 23.498 − 387 =
  24. 24.577 − 176 =
  25. 25.926 − 231 =
  26. 26.792 − 576 =
  27. 27.669 − 207 =
  28. 28.547 − 191 =
  29. 29.441 − 318 =
  30. 30.602 − 411 =
  31. 31.653 − 553 =
  32. 32.623 + 512 =
  33. 33.522 − 327 =
  34. 34.662 + 231 =
  35. 35.682 + 466 =
  36. 36.289 + 594 =
  37. 37.754 + 413 =
  38. 38.793 − 444 =
  39. 39.730 − 172 =
  40. 40.359 + 241 =

Answer key

  1. 720
  2. 471
  3. 377
  4. 613
  5. 620
  6. 1077
  7. 437
  8. 863
  9. 772
  10. 545
  11. 905
  12. 872
  13. 1195
  14. 631
  15. 1310
  16. 869
  17. 135
  18. 720
  19. 1111
  20. 385
  21. 364
  22. 536
  23. 111
  24. 401
  25. 695
  26. 216
  27. 462
  28. 356
  29. 123
  30. 191
  31. 100
  32. 1135
  33. 195
  34. 893
  35. 1148
  36. 883
  37. 1167
  38. 349
  39. 558
  40. 600

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