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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 950 · 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. 1.490 − 329 =
  2. 2.753 + 474 =
  3. 3.241 + 551 =
  4. 4.755 − 371 =
  5. 5.866 − 169 =
  6. 6.625 − 201 =
  7. 7.633 + 413 =
  8. 8.480 − 367 =
  9. 9.793 − 576 =
  10. 10.403 + 661 =
  11. 11.817 − 541 =
  12. 12.681 − 168 =
  13. 13.606 − 128 =
  14. 14.539 − 408 =
  15. 15.676 − 358 =
  16. 16.950 − 223 =
  17. 17.786 − 631 =
  18. 18.168 + 587 =
  19. 19.818 − 441 =
  20. 20.547 − 223 =
  21. 21.459 + 172 =
  22. 22.614 + 171 =
  23. 23.556 + 112 =
  24. 24.469 + 485 =
  25. 25.786 + 339 =
  26. 26.615 − 346 =
  27. 27.474 + 257 =
  28. 28.599 − 418 =
  29. 29.155 + 524 =
  30. 30.617 − 229 =
  31. 31.481 − 211 =
  32. 32.612 − 188 =
  33. 33.391 + 115 =
  34. 34.740 + 588 =
  35. 35.609 − 331 =
  36. 36.654 − 231 =
  37. 37.777 + 245 =
  38. 38.654 + 235 =
  39. 39.448 − 317 =
  40. 40.473 + 417 =

Answer key

  1. 161
  2. 1227
  3. 792
  4. 384
  5. 697
  6. 424
  7. 1046
  8. 113
  9. 217
  10. 1064
  11. 276
  12. 513
  13. 478
  14. 131
  15. 318
  16. 727
  17. 155
  18. 755
  19. 377
  20. 324
  21. 631
  22. 785
  23. 668
  24. 954
  25. 1125
  26. 269
  27. 731
  28. 181
  29. 679
  30. 388
  31. 270
  32. 424
  33. 506
  34. 1328
  35. 278
  36. 423
  37. 1022
  38. 889
  39. 131
  40. 890

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