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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 674 · 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. 1.607 + 362 =
  2. 2.511 − 345 =
  3. 3.618 − 512 =
  4. 4.472 − 352 =
  5. 5.444 − 122 =
  6. 6.589 − 359 =
  7. 7.309 + 188 =
  8. 8.471 − 138 =
  9. 9.209 + 142 =
  10. 10.182 + 137 =
  11. 11.532 − 134 =
  12. 12.986 − 418 =
  13. 13.617 + 354 =
  14. 14.481 + 554 =
  15. 15.611 + 651 =
  16. 16.202 + 161 =
  17. 17.264 + 639 =
  18. 18.484 + 219 =
  19. 19.677 − 127 =
  20. 20.246 + 683 =
  21. 21.267 + 135 =
  22. 22.471 − 339 =
  23. 23.577 + 172 =
  24. 24.583 + 639 =
  25. 25.474 + 131 =
  26. 26.984 − 487 =
  27. 27.230 + 679 =
  28. 28.446 − 191 =
  29. 29.633 + 511 =
  30. 30.306 + 497 =
  31. 31.596 − 233 =
  32. 32.473 − 161 =
  33. 33.373 + 293 =
  34. 34.138 + 244 =
  35. 35.170 + 673 =
  36. 36.771 + 221 =
  37. 37.476 − 269 =
  38. 38.194 + 206 =
  39. 39.945 − 774 =
  40. 40.552 + 267 =

Answer key

  1. 969
  2. 166
  3. 106
  4. 120
  5. 322
  6. 230
  7. 497
  8. 333
  9. 351
  10. 319
  11. 398
  12. 568
  13. 971
  14. 1035
  15. 1262
  16. 363
  17. 903
  18. 703
  19. 550
  20. 929
  21. 402
  22. 132
  23. 749
  24. 1222
  25. 605
  26. 497
  27. 909
  28. 255
  29. 1144
  30. 803
  31. 363
  32. 312
  33. 666
  34. 382
  35. 843
  36. 992
  37. 207
  38. 400
  39. 171
  40. 819

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