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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 66 · 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. 1.590 + 227 =
  2. 2.969 − 296 =
  3. 3.243 + 154 =
  4. 4.591 + 391 =
  5. 5.525 − 211 =
  6. 6.780 − 498 =
  7. 7.450 − 157 =
  8. 8.823 − 365 =
  9. 9.937 − 554 =
  10. 10.220 + 307 =
  11. 11.502 − 151 =
  12. 12.622 − 192 =
  13. 13.549 + 455 =
  14. 14.849 − 418 =
  15. 15.359 + 451 =
  16. 16.289 + 153 =
  17. 17.203 + 471 =
  18. 18.465 − 138 =
  19. 19.762 + 547 =
  20. 20.461 + 307 =
  21. 21.508 − 262 =
  22. 22.455 − 328 =
  23. 23.580 − 424 =
  24. 24.531 − 401 =
  25. 25.553 − 309 =
  26. 26.859 − 488 =
  27. 27.485 − 178 =
  28. 28.761 − 396 =
  29. 29.738 − 126 =
  30. 30.785 − 608 =
  31. 31.134 + 218 =
  32. 32.698 + 324 =
  33. 33.453 − 149 =
  34. 34.759 − 126 =
  35. 35.148 + 672 =
  36. 36.614 − 256 =
  37. 37.355 + 133 =
  38. 38.471 − 136 =
  39. 39.571 + 272 =
  40. 40.550 + 203 =

Answer key

  1. 817
  2. 673
  3. 397
  4. 982
  5. 314
  6. 282
  7. 293
  8. 458
  9. 383
  10. 527
  11. 351
  12. 430
  13. 1004
  14. 431
  15. 810
  16. 442
  17. 674
  18. 327
  19. 1309
  20. 768
  21. 246
  22. 127
  23. 156
  24. 130
  25. 244
  26. 371
  27. 307
  28. 365
  29. 612
  30. 177
  31. 352
  32. 1022
  33. 304
  34. 633
  35. 820
  36. 358
  37. 488
  38. 335
  39. 843
  40. 753

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