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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 641 · 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. 1.984 − 263 =
  2. 2.499 + 452 =
  3. 3.776 − 323 =
  4. 4.511 − 223 =
  5. 5.564 + 341 =
  6. 6.625 + 241 =
  7. 7.395 + 155 =
  8. 8.147 + 557 =
  9. 9.514 − 237 =
  10. 10.184 + 412 =
  11. 11.648 + 401 =
  12. 12.504 + 178 =
  13. 13.839 − 223 =
  14. 14.752 + 218 =
  15. 15.935 − 296 =
  16. 16.292 + 151 =
  17. 17.433 − 221 =
  18. 18.184 + 464 =
  19. 19.498 − 347 =
  20. 20.259 + 523 =
  21. 21.608 − 229 =
  22. 22.587 + 447 =
  23. 23.738 + 331 =
  24. 24.697 − 528 =
  25. 25.129 + 279 =
  26. 26.458 + 579 =
  27. 27.279 + 275 =
  28. 28.514 − 366 =
  29. 29.341 + 184 =
  30. 30.413 − 121 =
  31. 31.769 + 157 =
  32. 32.598 − 375 =
  33. 33.451 + 221 =
  34. 34.963 − 803 =
  35. 35.646 − 307 =
  36. 36.560 − 141 =
  37. 37.170 + 165 =
  38. 38.506 − 157 =
  39. 39.858 − 622 =
  40. 40.966 − 262 =

Answer key

  1. 721
  2. 951
  3. 453
  4. 288
  5. 905
  6. 866
  7. 550
  8. 704
  9. 277
  10. 596
  11. 1049
  12. 682
  13. 616
  14. 970
  15. 639
  16. 443
  17. 212
  18. 648
  19. 151
  20. 782
  21. 379
  22. 1034
  23. 1069
  24. 169
  25. 408
  26. 1037
  27. 554
  28. 148
  29. 525
  30. 292
  31. 926
  32. 223
  33. 672
  34. 160
  35. 339
  36. 419
  37. 335
  38. 349
  39. 236
  40. 704

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