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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 358 · 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. 1.295 + 685 =
  2. 2.212 + 155 =
  3. 3.750 + 126 =
  4. 4.297 + 572 =
  5. 5.218 + 282 =
  6. 6.376 + 223 =
  7. 7.701 + 205 =
  8. 8.812 − 464 =
  9. 9.458 + 221 =
  10. 10.521 − 131 =
  11. 11.544 − 376 =
  12. 12.440 − 189 =
  13. 13.657 − 191 =
  14. 14.765 + 665 =
  15. 15.518 − 358 =
  16. 16.673 + 425 =
  17. 17.164 + 569 =
  18. 18.735 − 576 =
  19. 19.527 + 252 =
  20. 20.280 + 595 =
  21. 21.632 − 445 =
  22. 22.739 + 301 =
  23. 23.525 + 189 =
  24. 24.416 + 596 =
  25. 25.172 + 231 =
  26. 26.529 − 275 =
  27. 27.762 − 467 =
  28. 28.184 + 228 =
  29. 29.810 − 178 =
  30. 30.724 + 253 =
  31. 31.676 − 539 =
  32. 32.384 + 315 =
  33. 33.605 − 392 =
  34. 34.782 − 444 =
  35. 35.529 − 217 =
  36. 36.854 − 754 =
  37. 37.742 + 441 =
  38. 38.154 + 127 =
  39. 39.864 − 238 =
  40. 40.692 − 365 =

Answer key

  1. 980
  2. 367
  3. 876
  4. 869
  5. 500
  6. 599
  7. 906
  8. 348
  9. 679
  10. 390
  11. 168
  12. 251
  13. 466
  14. 1430
  15. 160
  16. 1098
  17. 733
  18. 159
  19. 779
  20. 875
  21. 187
  22. 1040
  23. 714
  24. 1012
  25. 403
  26. 254
  27. 295
  28. 412
  29. 632
  30. 977
  31. 137
  32. 699
  33. 213
  34. 338
  35. 312
  36. 100
  37. 1183
  38. 281
  39. 626
  40. 327

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