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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 676 · 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. 1.236 + 194 =
  2. 2.415 − 225 =
  3. 3.259 + 163 =
  4. 4.650 + 186 =
  5. 5.433 + 299 =
  6. 6.412 − 289 =
  7. 7.545 + 672 =
  8. 8.434 + 251 =
  9. 9.483 + 153 =
  10. 10.856 − 403 =
  11. 11.756 − 531 =
  12. 12.178 + 249 =
  13. 13.442 − 272 =
  14. 14.495 + 244 =
  15. 15.309 + 619 =
  16. 16.914 − 131 =
  17. 17.518 + 535 =
  18. 18.702 − 203 =
  19. 19.705 − 195 =
  20. 20.311 + 271 =
  21. 21.745 + 461 =
  22. 22.761 − 495 =
  23. 23.333 + 559 =
  24. 24.487 − 303 =
  25. 25.270 + 127 =
  26. 26.584 + 278 =
  27. 27.929 − 196 =
  28. 28.442 + 511 =
  29. 29.381 + 611 =
  30. 30.761 − 423 =
  31. 31.705 + 143 =
  32. 32.240 + 136 =
  33. 33.533 + 444 =
  34. 34.483 + 624 =
  35. 35.431 + 278 =
  36. 36.175 + 526 =
  37. 37.721 + 386 =
  38. 38.497 + 465 =
  39. 39.890 − 462 =
  40. 40.202 + 219 =

Answer key

  1. 430
  2. 190
  3. 422
  4. 836
  5. 732
  6. 123
  7. 1217
  8. 685
  9. 636
  10. 453
  11. 225
  12. 427
  13. 170
  14. 739
  15. 928
  16. 783
  17. 1053
  18. 499
  19. 510
  20. 582
  21. 1206
  22. 266
  23. 892
  24. 184
  25. 397
  26. 862
  27. 733
  28. 953
  29. 992
  30. 338
  31. 848
  32. 376
  33. 977
  34. 1107
  35. 709
  36. 701
  37. 1107
  38. 962
  39. 428
  40. 421

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