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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 786 · 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. 1.824 − 391 =
  2. 2.659 + 578 =
  3. 3.689 + 248 =
  4. 4.399 + 355 =
  5. 5.559 + 593 =
  6. 6.716 − 404 =
  7. 7.148 + 333 =
  8. 8.247 + 482 =
  9. 9.134 + 462 =
  10. 10.673 + 191 =
  11. 11.583 + 197 =
  12. 12.848 − 654 =
  13. 13.790 − 642 =
  14. 14.890 − 544 =
  15. 15.496 − 136 =
  16. 16.383 + 309 =
  17. 17.431 + 185 =
  18. 18.793 − 208 =
  19. 19.264 + 132 =
  20. 20.427 − 204 =
  21. 21.193 + 611 =
  22. 22.386 + 219 =
  23. 23.167 + 174 =
  24. 24.650 + 586 =
  25. 25.518 − 375 =
  26. 26.443 + 603 =
  27. 27.465 + 672 =
  28. 28.587 + 433 =
  29. 29.393 + 647 =
  30. 30.669 − 211 =
  31. 31.521 − 379 =
  32. 32.659 − 419 =
  33. 33.238 + 647 =
  34. 34.636 + 674 =
  35. 35.716 − 236 =
  36. 36.531 − 385 =
  37. 37.561 − 341 =
  38. 38.728 − 312 =
  39. 39.482 − 319 =
  40. 40.141 + 381 =

Answer key

  1. 433
  2. 1237
  3. 937
  4. 754
  5. 1152
  6. 312
  7. 481
  8. 729
  9. 596
  10. 864
  11. 780
  12. 194
  13. 148
  14. 346
  15. 360
  16. 692
  17. 616
  18. 585
  19. 396
  20. 223
  21. 804
  22. 605
  23. 341
  24. 1236
  25. 143
  26. 1046
  27. 1137
  28. 1020
  29. 1040
  30. 458
  31. 142
  32. 240
  33. 885
  34. 1310
  35. 480
  36. 146
  37. 220
  38. 416
  39. 163
  40. 522

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