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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 136 · 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. 1.294 + 131 =
  2. 2.744 + 281 =
  3. 3.675 + 581 =
  4. 4.857 − 342 =
  5. 5.686 − 474 =
  6. 6.522 + 338 =
  7. 7.681 + 303 =
  8. 8.671 − 307 =
  9. 9.482 + 172 =
  10. 10.628 + 582 =
  11. 11.384 + 127 =
  12. 12.495 − 271 =
  13. 13.420 − 316 =
  14. 14.980 − 267 =
  15. 15.700 + 281 =
  16. 16.149 + 192 =
  17. 17.730 + 435 =
  18. 18.967 − 789 =
  19. 19.855 − 466 =
  20. 20.749 + 142 =
  21. 21.550 + 442 =
  22. 22.452 − 345 =
  23. 23.486 + 273 =
  24. 24.390 + 318 =
  25. 25.432 + 173 =
  26. 26.728 + 621 =
  27. 27.409 + 366 =
  28. 28.203 + 521 =
  29. 29.352 + 291 =
  30. 30.485 − 123 =
  31. 31.449 − 115 =
  32. 32.318 + 592 =
  33. 33.569 − 414 =
  34. 34.311 + 164 =
  35. 35.716 − 581 =
  36. 36.208 + 164 =
  37. 37.755 + 505 =
  38. 38.683 + 438 =
  39. 39.379 + 484 =
  40. 40.211 + 151 =

Answer key

  1. 425
  2. 1025
  3. 1256
  4. 515
  5. 212
  6. 860
  7. 984
  8. 364
  9. 654
  10. 1210
  11. 511
  12. 224
  13. 104
  14. 713
  15. 981
  16. 341
  17. 1165
  18. 178
  19. 389
  20. 891
  21. 992
  22. 107
  23. 759
  24. 708
  25. 605
  26. 1349
  27. 775
  28. 724
  29. 643
  30. 362
  31. 334
  32. 910
  33. 155
  34. 475
  35. 135
  36. 372
  37. 1260
  38. 1121
  39. 863
  40. 362

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