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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 470 · 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. 1.477 + 361 =
  2. 2.636 − 161 =
  3. 3.783 − 381 =
  4. 4.299 + 382 =
  5. 5.955 − 288 =
  6. 6.723 + 128 =
  7. 7.438 + 529 =
  8. 8.734 + 335 =
  9. 9.238 + 309 =
  10. 10.518 − 394 =
  11. 11.339 + 211 =
  12. 12.608 − 124 =
  13. 13.577 − 126 =
  14. 14.369 + 482 =
  15. 15.709 − 369 =
  16. 16.733 + 174 =
  17. 17.722 − 361 =
  18. 18.156 + 254 =
  19. 19.559 + 134 =
  20. 20.726 − 461 =
  21. 21.420 + 561 =
  22. 22.483 − 161 =
  23. 23.763 − 373 =
  24. 24.383 + 664 =
  25. 25.575 − 465 =
  26. 26.744 − 311 =
  27. 27.696 − 419 =
  28. 28.500 − 121 =
  29. 29.740 − 476 =
  30. 30.562 + 152 =
  31. 31.565 − 292 =
  32. 32.243 + 258 =
  33. 33.659 + 492 =
  34. 34.611 − 411 =
  35. 35.135 + 268 =
  36. 36.744 − 288 =
  37. 37.902 − 758 =
  38. 38.529 − 153 =
  39. 39.541 + 624 =
  40. 40.462 + 113 =

Answer key

  1. 838
  2. 475
  3. 402
  4. 681
  5. 667
  6. 851
  7. 967
  8. 1069
  9. 547
  10. 124
  11. 550
  12. 484
  13. 451
  14. 851
  15. 340
  16. 907
  17. 361
  18. 410
  19. 693
  20. 265
  21. 981
  22. 322
  23. 390
  24. 1047
  25. 110
  26. 433
  27. 277
  28. 379
  29. 264
  30. 714
  31. 273
  32. 501
  33. 1151
  34. 200
  35. 403
  36. 456
  37. 144
  38. 376
  39. 1165
  40. 575

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