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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 879 · 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. 1.500 − 229 =
  2. 2.435 − 296 =
  3. 3.723 + 636 =
  4. 4.531 − 345 =
  5. 5.497 − 278 =
  6. 6.273 + 638 =
  7. 7.897 − 502 =
  8. 8.738 − 623 =
  9. 9.136 + 256 =
  10. 10.481 − 211 =
  11. 11.645 + 157 =
  12. 12.486 + 176 =
  13. 13.708 + 231 =
  14. 14.607 + 181 =
  15. 15.662 + 272 =
  16. 16.604 − 331 =
  17. 17.525 + 321 =
  18. 18.588 + 637 =
  19. 19.456 + 503 =
  20. 20.537 + 346 =
  21. 21.213 + 162 =
  22. 22.528 − 323 =
  23. 23.639 − 522 =
  24. 24.315 + 415 =
  25. 25.190 + 443 =
  26. 26.470 − 336 =
  27. 27.479 − 149 =
  28. 28.240 + 411 =
  29. 29.557 − 168 =
  30. 30.937 − 222 =
  31. 31.587 + 245 =
  32. 32.647 + 212 =
  33. 33.580 + 627 =
  34. 34.277 + 216 =
  35. 35.794 − 204 =
  36. 36.301 + 431 =
  37. 37.489 − 219 =
  38. 38.292 + 131 =
  39. 39.862 − 155 =
  40. 40.396 + 348 =

Answer key

  1. 271
  2. 139
  3. 1359
  4. 186
  5. 219
  6. 911
  7. 395
  8. 115
  9. 392
  10. 270
  11. 802
  12. 662
  13. 939
  14. 788
  15. 934
  16. 273
  17. 846
  18. 1225
  19. 959
  20. 883
  21. 375
  22. 205
  23. 117
  24. 730
  25. 633
  26. 134
  27. 330
  28. 651
  29. 389
  30. 715
  31. 832
  32. 859
  33. 1207
  34. 493
  35. 590
  36. 732
  37. 270
  38. 423
  39. 707
  40. 744

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