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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 834 · 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. 1.583 + 469 =
  2. 2.325 + 426 =
  3. 3.127 + 183 =
  4. 4.674 − 273 =
  5. 5.573 + 498 =
  6. 6.566 − 182 =
  7. 7.678 − 378 =
  8. 8.581 − 385 =
  9. 9.602 − 169 =
  10. 10.712 − 298 =
  11. 11.682 + 315 =
  12. 12.157 + 431 =
  13. 13.481 − 233 =
  14. 14.740 + 521 =
  15. 15.178 + 191 =
  16. 16.726 + 115 =
  17. 17.499 + 199 =
  18. 18.608 + 511 =
  19. 19.446 − 324 =
  20. 20.617 + 679 =
  21. 21.384 + 328 =
  22. 22.140 + 187 =
  23. 23.224 + 491 =
  24. 24.749 − 441 =
  25. 25.715 − 505 =
  26. 26.655 + 518 =
  27. 27.373 + 261 =
  28. 28.891 − 539 =
  29. 29.514 + 634 =
  30. 30.602 − 154 =
  31. 31.732 + 386 =
  32. 32.278 + 661 =
  33. 33.677 + 572 =
  34. 34.589 − 318 =
  35. 35.963 − 742 =
  36. 36.836 − 525 =
  37. 37.629 − 139 =
  38. 38.288 + 621 =
  39. 39.799 − 217 =
  40. 40.135 + 681 =

Answer key

  1. 1052
  2. 751
  3. 310
  4. 401
  5. 1071
  6. 384
  7. 300
  8. 196
  9. 433
  10. 414
  11. 997
  12. 588
  13. 248
  14. 1261
  15. 369
  16. 841
  17. 698
  18. 1119
  19. 122
  20. 1296
  21. 712
  22. 327
  23. 715
  24. 308
  25. 210
  26. 1173
  27. 634
  28. 352
  29. 1148
  30. 448
  31. 1118
  32. 939
  33. 1249
  34. 271
  35. 221
  36. 311
  37. 490
  38. 909
  39. 582
  40. 816

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