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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 174 · 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. 1.514 + 205 =
  2. 2.972 − 248 =
  3. 3.708 − 185 =
  4. 4.545 − 367 =
  5. 5.499 + 677 =
  6. 6.674 + 572 =
  7. 7.516 − 335 =
  8. 8.545 − 205 =
  9. 9.473 − 175 =
  10. 10.192 + 204 =
  11. 11.703 + 668 =
  12. 12.985 − 872 =
  13. 13.565 − 236 =
  14. 14.241 + 547 =
  15. 15.362 + 223 =
  16. 16.715 − 251 =
  17. 17.475 + 309 =
  18. 18.581 − 196 =
  19. 19.447 − 205 =
  20. 20.468 − 347 =
  21. 21.532 + 431 =
  22. 22.236 + 216 =
  23. 23.564 + 363 =
  24. 24.713 + 369 =
  25. 25.825 − 543 =
  26. 26.750 − 135 =
  27. 27.840 − 459 =
  28. 28.261 + 144 =
  29. 29.412 − 221 =
  30. 30.467 − 211 =
  31. 31.703 − 403 =
  32. 32.258 + 414 =
  33. 33.600 + 569 =
  34. 34.920 − 322 =
  35. 35.537 + 173 =
  36. 36.219 + 608 =
  37. 37.683 − 464 =
  38. 38.459 − 299 =
  39. 39.405 + 334 =
  40. 40.452 − 129 =

Answer key

  1. 719
  2. 724
  3. 523
  4. 178
  5. 1176
  6. 1246
  7. 181
  8. 340
  9. 298
  10. 396
  11. 1371
  12. 113
  13. 329
  14. 788
  15. 585
  16. 464
  17. 784
  18. 385
  19. 242
  20. 121
  21. 963
  22. 452
  23. 927
  24. 1082
  25. 282
  26. 615
  27. 381
  28. 405
  29. 191
  30. 256
  31. 300
  32. 672
  33. 1169
  34. 598
  35. 710
  36. 827
  37. 219
  38. 160
  39. 739
  40. 323

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