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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 190 · 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. 1.626 + 578 =
  2. 2.778 + 491 =
  3. 3.542 − 425 =
  4. 4.556 + 681 =
  5. 5.623 − 285 =
  6. 6.442 + 401 =
  7. 7.720 − 563 =
  8. 8.951 − 595 =
  9. 9.459 − 122 =
  10. 10.807 − 316 =
  11. 11.493 + 462 =
  12. 12.457 + 678 =
  13. 13.963 − 803 =
  14. 14.682 + 377 =
  15. 15.413 + 236 =
  16. 16.461 − 243 =
  17. 17.519 + 149 =
  18. 18.259 + 373 =
  19. 19.700 + 256 =
  20. 20.549 − 157 =
  21. 21.926 − 391 =
  22. 22.225 + 231 =
  23. 23.693 + 628 =
  24. 24.450 − 151 =
  25. 25.444 − 207 =
  26. 26.543 + 286 =
  27. 27.163 + 654 =
  28. 28.540 − 131 =
  29. 29.553 + 356 =
  30. 30.279 + 141 =
  31. 31.463 + 301 =
  32. 32.257 + 501 =
  33. 33.153 + 492 =
  34. 34.438 + 351 =
  35. 35.342 + 181 =
  36. 36.926 − 164 =
  37. 37.508 + 286 =
  38. 38.966 − 639 =
  39. 39.757 − 651 =
  40. 40.515 − 261 =

Answer key

  1. 1204
  2. 1269
  3. 117
  4. 1237
  5. 338
  6. 843
  7. 157
  8. 356
  9. 337
  10. 491
  11. 955
  12. 1135
  13. 160
  14. 1059
  15. 649
  16. 218
  17. 668
  18. 632
  19. 956
  20. 392
  21. 535
  22. 456
  23. 1321
  24. 299
  25. 237
  26. 829
  27. 817
  28. 409
  29. 909
  30. 420
  31. 764
  32. 758
  33. 645
  34. 789
  35. 523
  36. 762
  37. 794
  38. 327
  39. 106
  40. 254

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