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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 306 · 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. 1.441 + 601 =
  2. 2.453 + 534 =
  3. 3.517 + 219 =
  4. 4.704 + 199 =
  5. 5.761 + 122 =
  6. 6.646 + 231 =
  7. 7.387 + 307 =
  8. 8.636 + 502 =
  9. 9.637 + 161 =
  10. 10.678 − 309 =
  11. 11.926 − 141 =
  12. 12.471 − 371 =
  13. 13.952 − 206 =
  14. 14.729 + 528 =
  15. 15.867 − 132 =
  16. 16.563 + 286 =
  17. 17.170 + 613 =
  18. 18.530 − 367 =
  19. 19.531 − 331 =
  20. 20.639 + 392 =
  21. 21.523 − 132 =
  22. 22.630 − 196 =
  23. 23.144 + 156 =
  24. 24.136 + 148 =
  25. 25.384 + 251 =
  26. 26.147 + 131 =
  27. 27.712 + 211 =
  28. 28.426 − 143 =
  29. 29.954 − 821 =
  30. 30.468 + 279 =
  31. 31.133 + 651 =
  32. 32.782 + 261 =
  33. 33.691 − 215 =
  34. 34.784 − 645 =
  35. 35.634 − 361 =
  36. 36.379 + 443 =
  37. 37.364 + 471 =
  38. 38.705 + 225 =
  39. 39.643 + 457 =
  40. 40.670 − 257 =

Answer key

  1. 1042
  2. 987
  3. 736
  4. 903
  5. 883
  6. 877
  7. 694
  8. 1138
  9. 798
  10. 369
  11. 785
  12. 100
  13. 746
  14. 1257
  15. 735
  16. 849
  17. 783
  18. 163
  19. 200
  20. 1031
  21. 391
  22. 434
  23. 300
  24. 284
  25. 635
  26. 278
  27. 923
  28. 283
  29. 133
  30. 747
  31. 784
  32. 1043
  33. 476
  34. 139
  35. 273
  36. 822
  37. 835
  38. 930
  39. 1100
  40. 413

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