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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 246 · 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. 1.272 + 289 =
  2. 2.503 − 127 =
  3. 3.544 − 319 =
  4. 4.245 + 451 =
  5. 5.135 + 383 =
  6. 6.836 − 122 =
  7. 7.323 + 495 =
  8. 8.790 − 644 =
  9. 9.142 + 533 =
  10. 10.301 + 382 =
  11. 11.819 − 276 =
  12. 12.650 + 203 =
  13. 13.781 − 381 =
  14. 14.354 + 489 =
  15. 15.458 − 295 =
  16. 16.641 + 677 =
  17. 17.771 − 533 =
  18. 18.562 − 441 =
  19. 19.716 − 151 =
  20. 20.560 − 418 =
  21. 21.311 + 259 =
  22. 22.487 + 168 =
  23. 23.708 + 534 =
  24. 24.829 − 332 =
  25. 25.507 − 377 =
  26. 26.704 − 171 =
  27. 27.227 + 513 =
  28. 28.560 − 452 =
  29. 29.470 + 318 =
  30. 30.697 + 502 =
  31. 31.940 − 678 =
  32. 32.125 + 342 =
  33. 33.183 + 133 =
  34. 34.698 − 343 =
  35. 35.126 + 179 =
  36. 36.157 + 462 =
  37. 37.552 − 266 =
  38. 38.528 − 162 =
  39. 39.611 + 262 =
  40. 40.644 + 391 =

Answer key

  1. 561
  2. 376
  3. 225
  4. 696
  5. 518
  6. 714
  7. 818
  8. 146
  9. 675
  10. 683
  11. 543
  12. 853
  13. 400
  14. 843
  15. 163
  16. 1318
  17. 238
  18. 121
  19. 565
  20. 142
  21. 570
  22. 655
  23. 1242
  24. 497
  25. 130
  26. 533
  27. 740
  28. 108
  29. 788
  30. 1199
  31. 262
  32. 467
  33. 316
  34. 355
  35. 305
  36. 619
  37. 286
  38. 366
  39. 873
  40. 1035

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