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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 445 · 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. 1.731 − 624 =
  2. 2.175 + 238 =
  3. 3.235 + 465 =
  4. 4.206 + 217 =
  5. 5.725 + 361 =
  6. 6.417 + 191 =
  7. 7.564 − 225 =
  8. 8.544 + 601 =
  9. 9.716 + 277 =
  10. 10.125 + 659 =
  11. 11.806 − 276 =
  12. 12.315 + 679 =
  13. 13.481 + 201 =
  14. 14.960 − 138 =
  15. 15.165 + 212 =
  16. 16.788 + 235 =
  17. 17.252 + 396 =
  18. 18.540 − 335 =
  19. 19.250 + 592 =
  20. 20.514 + 618 =
  21. 21.493 − 298 =
  22. 22.526 − 392 =
  23. 23.375 + 561 =
  24. 24.520 − 131 =
  25. 25.667 − 552 =
  26. 26.979 − 168 =
  27. 27.942 − 548 =
  28. 28.746 + 582 =
  29. 29.716 + 345 =
  30. 30.958 − 171 =
  31. 31.974 − 654 =
  32. 32.458 − 339 =
  33. 33.155 + 354 =
  34. 34.370 + 313 =
  35. 35.474 + 628 =
  36. 36.498 + 573 =
  37. 37.736 − 219 =
  38. 38.621 + 252 =
  39. 39.439 + 383 =
  40. 40.504 + 325 =

Answer key

  1. 107
  2. 413
  3. 700
  4. 423
  5. 1086
  6. 608
  7. 339
  8. 1145
  9. 993
  10. 784
  11. 530
  12. 994
  13. 682
  14. 822
  15. 377
  16. 1023
  17. 648
  18. 205
  19. 842
  20. 1132
  21. 195
  22. 134
  23. 936
  24. 389
  25. 115
  26. 811
  27. 394
  28. 1328
  29. 1061
  30. 787
  31. 320
  32. 119
  33. 509
  34. 683
  35. 1102
  36. 1071
  37. 517
  38. 873
  39. 822
  40. 829

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