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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 907 · 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. 1.477 − 341 =
  2. 2.397 + 242 =
  3. 3.636 + 192 =
  4. 4.154 + 627 =
  5. 5.177 + 459 =
  6. 6.625 − 469 =
  7. 7.596 + 613 =
  8. 8.591 + 217 =
  9. 9.985 − 583 =
  10. 10.527 − 254 =
  11. 11.749 + 309 =
  12. 12.877 − 394 =
  13. 13.205 + 358 =
  14. 14.748 + 619 =
  15. 15.698 + 114 =
  16. 16.904 − 735 =
  17. 17.515 − 161 =
  18. 18.619 + 174 =
  19. 19.352 + 685 =
  20. 20.286 + 539 =
  21. 21.613 − 157 =
  22. 22.756 − 125 =
  23. 23.775 + 296 =
  24. 24.592 + 446 =
  25. 25.738 − 232 =
  26. 26.758 − 406 =
  27. 27.505 + 632 =
  28. 28.966 − 851 =
  29. 29.564 + 141 =
  30. 30.842 − 554 =
  31. 31.494 + 424 =
  32. 32.771 + 291 =
  33. 33.160 + 212 =
  34. 34.542 − 372 =
  35. 35.591 − 407 =
  36. 36.682 + 515 =
  37. 37.489 − 197 =
  38. 38.226 + 301 =
  39. 39.445 − 168 =
  40. 40.719 + 661 =

Answer key

  1. 136
  2. 639
  3. 828
  4. 781
  5. 636
  6. 156
  7. 1209
  8. 808
  9. 402
  10. 273
  11. 1058
  12. 483
  13. 563
  14. 1367
  15. 812
  16. 169
  17. 354
  18. 793
  19. 1037
  20. 825
  21. 456
  22. 631
  23. 1071
  24. 1038
  25. 506
  26. 352
  27. 1137
  28. 115
  29. 705
  30. 288
  31. 918
  32. 1062
  33. 372
  34. 170
  35. 184
  36. 1197
  37. 292
  38. 527
  39. 277
  40. 1380

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