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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 930 · 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. 1.672 + 599 =
  2. 2.471 − 167 =
  3. 3.262 + 681 =
  4. 4.138 + 568 =
  5. 5.956 − 432 =
  6. 6.525 + 279 =
  7. 7.947 − 339 =
  8. 8.705 − 191 =
  9. 9.440 − 192 =
  10. 10.186 + 253 =
  11. 11.523 − 322 =
  12. 12.574 − 148 =
  13. 13.215 + 198 =
  14. 14.975 − 662 =
  15. 15.469 + 684 =
  16. 16.852 − 716 =
  17. 17.359 + 193 =
  18. 18.702 − 408 =
  19. 19.763 − 451 =
  20. 20.432 + 534 =
  21. 21.203 + 401 =
  22. 22.514 − 354 =
  23. 23.695 + 297 =
  24. 24.564 − 154 =
  25. 25.365 + 178 =
  26. 26.647 + 211 =
  27. 27.611 + 495 =
  28. 28.726 + 134 =
  29. 29.674 − 175 =
  30. 30.963 − 691 =
  31. 31.712 + 401 =
  32. 32.638 − 238 =
  33. 33.980 − 306 =
  34. 34.839 − 181 =
  35. 35.322 + 438 =
  36. 36.416 − 179 =
  37. 37.327 + 254 =
  38. 38.958 − 607 =
  39. 39.604 + 393 =
  40. 40.792 − 122 =

Answer key

  1. 1271
  2. 304
  3. 943
  4. 706
  5. 524
  6. 804
  7. 608
  8. 514
  9. 248
  10. 439
  11. 201
  12. 426
  13. 413
  14. 313
  15. 1153
  16. 136
  17. 552
  18. 294
  19. 312
  20. 966
  21. 604
  22. 160
  23. 992
  24. 410
  25. 543
  26. 858
  27. 1106
  28. 860
  29. 499
  30. 272
  31. 1113
  32. 400
  33. 674
  34. 658
  35. 760
  36. 237
  37. 581
  38. 351
  39. 997
  40. 670

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