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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 595 · 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. 1.656 + 266 =
  2. 2.177 + 543 =
  3. 3.526 + 503 =
  4. 4.725 + 641 =
  5. 5.548 − 138 =
  6. 6.146 + 527 =
  7. 7.591 + 219 =
  8. 8.891 − 639 =
  9. 9.428 − 124 =
  10. 10.304 + 616 =
  11. 11.130 + 549 =
  12. 12.491 + 439 =
  13. 13.773 − 331 =
  14. 14.354 + 447 =
  15. 15.210 + 426 =
  16. 16.899 − 128 =
  17. 17.525 − 138 =
  18. 18.435 − 147 =
  19. 19.911 − 736 =
  20. 20.760 + 507 =
  21. 21.270 + 491 =
  22. 22.781 + 117 =
  23. 23.236 + 207 =
  24. 24.520 − 169 =
  25. 25.472 + 261 =
  26. 26.691 + 574 =
  27. 27.448 − 254 =
  28. 28.212 + 187 =
  29. 29.760 − 542 =
  30. 30.732 + 281 =
  31. 31.566 − 319 =
  32. 32.520 + 308 =
  33. 33.986 − 878 =
  34. 34.572 + 677 =
  35. 35.776 + 337 =
  36. 36.561 + 554 =
  37. 37.858 − 744 =
  38. 38.620 + 181 =
  39. 39.641 − 194 =
  40. 40.583 − 232 =

Answer key

  1. 922
  2. 720
  3. 1029
  4. 1366
  5. 410
  6. 673
  7. 810
  8. 252
  9. 304
  10. 920
  11. 679
  12. 930
  13. 442
  14. 801
  15. 636
  16. 771
  17. 387
  18. 288
  19. 175
  20. 1267
  21. 761
  22. 898
  23. 443
  24. 351
  25. 733
  26. 1265
  27. 194
  28. 399
  29. 218
  30. 1013
  31. 247
  32. 828
  33. 108
  34. 1249
  35. 1113
  36. 1115
  37. 114
  38. 801
  39. 447
  40. 351

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