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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 251 · 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. 1.137 + 154 =
  2. 2.872 − 198 =
  3. 3.651 + 561 =
  4. 4.366 + 452 =
  5. 5.158 + 159 =
  6. 6.297 + 327 =
  7. 7.475 + 606 =
  8. 8.230 + 161 =
  9. 9.328 + 351 =
  10. 10.425 + 553 =
  11. 11.781 − 334 =
  12. 12.460 − 164 =
  13. 13.208 + 545 =
  14. 14.641 − 479 =
  15. 15.150 + 261 =
  16. 16.876 − 371 =
  17. 17.845 − 459 =
  18. 18.477 + 491 =
  19. 19.475 + 304 =
  20. 20.477 − 171 =
  21. 21.773 + 306 =
  22. 22.711 + 643 =
  23. 23.724 − 381 =
  24. 24.674 − 545 =
  25. 25.491 − 113 =
  26. 26.563 + 341 =
  27. 27.567 − 116 =
  28. 28.414 − 169 =
  29. 29.491 − 272 =
  30. 30.494 − 244 =
  31. 31.758 + 269 =
  32. 32.751 + 609 =
  33. 33.490 − 159 =
  34. 34.533 − 432 =
  35. 35.713 + 288 =
  36. 36.473 + 323 =
  37. 37.257 + 581 =
  38. 38.134 + 228 =
  39. 39.687 + 295 =
  40. 40.961 − 697 =

Answer key

  1. 291
  2. 674
  3. 1212
  4. 818
  5. 317
  6. 624
  7. 1081
  8. 391
  9. 679
  10. 978
  11. 447
  12. 296
  13. 753
  14. 162
  15. 411
  16. 505
  17. 386
  18. 968
  19. 779
  20. 306
  21. 1079
  22. 1354
  23. 343
  24. 129
  25. 378
  26. 904
  27. 451
  28. 245
  29. 219
  30. 250
  31. 1027
  32. 1360
  33. 331
  34. 101
  35. 1001
  36. 796
  37. 838
  38. 362
  39. 982
  40. 264

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