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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 271 · 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. 1.497 − 133 =
  2. 2.934 − 678 =
  3. 3.932 − 805 =
  4. 4.824 − 274 =
  5. 5.914 − 755 =
  6. 6.878 − 575 =
  7. 7.562 − 409 =
  8. 8.341 + 151 =
  9. 9.779 + 624 =
  10. 10.385 + 384 =
  11. 11.279 + 523 =
  12. 12.641 + 446 =
  13. 13.653 − 119 =
  14. 14.737 − 511 =
  15. 15.522 + 496 =
  16. 16.124 + 566 =
  17. 17.466 − 281 =
  18. 18.449 − 328 =
  19. 19.511 − 315 =
  20. 20.330 + 462 =
  21. 21.437 + 513 =
  22. 22.502 − 149 =
  23. 23.677 − 551 =
  24. 24.598 + 413 =
  25. 25.927 − 656 =
  26. 26.556 − 211 =
  27. 27.634 − 359 =
  28. 28.291 + 141 =
  29. 29.442 − 166 =
  30. 30.135 + 143 =
  31. 31.516 + 163 =
  32. 32.260 + 601 =
  33. 33.425 + 455 =
  34. 34.192 + 616 =
  35. 35.339 + 669 =
  36. 36.862 − 505 =
  37. 37.386 + 123 =
  38. 38.241 + 367 =
  39. 39.710 − 145 =
  40. 40.754 + 293 =

Answer key

  1. 364
  2. 256
  3. 127
  4. 550
  5. 159
  6. 303
  7. 153
  8. 492
  9. 1403
  10. 769
  11. 802
  12. 1087
  13. 534
  14. 226
  15. 1018
  16. 690
  17. 185
  18. 121
  19. 196
  20. 792
  21. 950
  22. 353
  23. 126
  24. 1011
  25. 271
  26. 345
  27. 275
  28. 432
  29. 276
  30. 278
  31. 679
  32. 861
  33. 880
  34. 808
  35. 1008
  36. 357
  37. 509
  38. 608
  39. 565
  40. 1047

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