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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 194 · 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. 1.456 + 212 =
  2. 2.958 − 797 =
  3. 3.753 + 402 =
  4. 4.646 − 285 =
  5. 5.279 + 496 =
  6. 6.671 − 138 =
  7. 7.663 + 318 =
  8. 8.883 − 518 =
  9. 9.321 + 181 =
  10. 10.141 + 425 =
  11. 11.834 − 507 =
  12. 12.970 − 226 =
  13. 13.730 + 489 =
  14. 14.559 − 238 =
  15. 15.713 + 146 =
  16. 16.598 − 168 =
  17. 17.306 + 438 =
  18. 18.827 − 462 =
  19. 19.288 + 451 =
  20. 20.645 + 141 =
  21. 21.550 − 141 =
  22. 22.245 + 619 =
  23. 23.389 + 585 =
  24. 24.202 + 333 =
  25. 25.512 − 373 =
  26. 26.787 + 432 =
  27. 27.716 − 166 =
  28. 28.982 − 772 =
  29. 29.213 + 551 =
  30. 30.159 + 683 =
  31. 31.611 − 271 =
  32. 32.368 + 172 =
  33. 33.645 − 422 =
  34. 34.233 + 233 =
  35. 35.564 + 582 =
  36. 36.739 − 425 =
  37. 37.865 − 231 =
  38. 38.148 + 288 =
  39. 39.464 − 171 =
  40. 40.407 + 389 =

Answer key

  1. 668
  2. 161
  3. 1155
  4. 361
  5. 775
  6. 533
  7. 981
  8. 365
  9. 502
  10. 566
  11. 327
  12. 744
  13. 1219
  14. 321
  15. 859
  16. 430
  17. 744
  18. 365
  19. 739
  20. 786
  21. 409
  22. 864
  23. 974
  24. 535
  25. 139
  26. 1219
  27. 550
  28. 210
  29. 764
  30. 842
  31. 340
  32. 540
  33. 223
  34. 466
  35. 1146
  36. 314
  37. 634
  38. 436
  39. 293
  40. 796

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