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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 561 · 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. 1.300 + 283 =
  2. 2.746 + 182 =
  3. 3.228 + 228 =
  4. 4.508 + 565 =
  5. 5.622 + 186 =
  6. 6.670 + 231 =
  7. 7.152 + 213 =
  8. 8.479 − 291 =
  9. 9.139 + 341 =
  10. 10.593 − 273 =
  11. 11.524 + 536 =
  12. 12.549 − 441 =
  13. 13.524 − 337 =
  14. 14.691 − 441 =
  15. 15.271 + 598 =
  16. 16.450 − 195 =
  17. 17.392 + 132 =
  18. 18.503 + 236 =
  19. 19.781 + 439 =
  20. 20.696 − 269 =
  21. 21.656 + 661 =
  22. 22.893 − 524 =
  23. 23.447 − 193 =
  24. 24.294 + 663 =
  25. 25.736 − 379 =
  26. 26.202 + 556 =
  27. 27.345 + 585 =
  28. 28.672 + 433 =
  29. 29.928 − 502 =
  30. 30.374 + 152 =
  31. 31.772 − 619 =
  32. 32.988 − 567 =
  33. 33.438 − 119 =
  34. 34.320 + 252 =
  35. 35.923 − 156 =
  36. 36.671 + 641 =
  37. 37.534 + 634 =
  38. 38.507 − 181 =
  39. 39.461 − 166 =
  40. 40.684 + 224 =

Answer key

  1. 583
  2. 928
  3. 456
  4. 1073
  5. 808
  6. 901
  7. 365
  8. 188
  9. 480
  10. 320
  11. 1060
  12. 108
  13. 187
  14. 250
  15. 869
  16. 255
  17. 524
  18. 739
  19. 1220
  20. 427
  21. 1317
  22. 369
  23. 254
  24. 957
  25. 357
  26. 758
  27. 930
  28. 1105
  29. 426
  30. 526
  31. 153
  32. 421
  33. 319
  34. 572
  35. 767
  36. 1312
  37. 1168
  38. 326
  39. 295
  40. 908

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