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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 912 · 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. 1.712 + 174 =
  2. 2.402 + 636 =
  3. 3.435 − 233 =
  4. 4.940 − 143 =
  5. 5.633 − 528 =
  6. 6.578 + 491 =
  7. 7.302 + 501 =
  8. 8.894 − 178 =
  9. 9.787 + 324 =
  10. 10.867 − 582 =
  11. 11.515 + 171 =
  12. 12.240 + 211 =
  13. 13.660 + 411 =
  14. 14.220 + 239 =
  15. 15.911 − 158 =
  16. 16.627 − 201 =
  17. 17.167 + 305 =
  18. 18.455 − 119 =
  19. 19.723 + 218 =
  20. 20.192 + 569 =
  21. 21.798 − 253 =
  22. 22.152 + 675 =
  23. 23.855 − 147 =
  24. 24.543 + 397 =
  25. 25.288 + 331 =
  26. 26.555 − 381 =
  27. 27.329 + 654 =
  28. 28.341 + 641 =
  29. 29.763 − 169 =
  30. 30.697 − 587 =
  31. 31.935 − 583 =
  32. 32.391 + 582 =
  33. 33.275 + 282 =
  34. 34.239 + 684 =
  35. 35.766 − 578 =
  36. 36.472 + 683 =
  37. 37.910 − 716 =
  38. 38.193 + 161 =
  39. 39.743 − 154 =
  40. 40.545 + 366 =

Answer key

  1. 886
  2. 1038
  3. 202
  4. 797
  5. 105
  6. 1069
  7. 803
  8. 716
  9. 1111
  10. 285
  11. 686
  12. 451
  13. 1071
  14. 459
  15. 753
  16. 426
  17. 472
  18. 336
  19. 941
  20. 761
  21. 545
  22. 827
  23. 708
  24. 940
  25. 619
  26. 174
  27. 983
  28. 982
  29. 594
  30. 110
  31. 352
  32. 973
  33. 557
  34. 923
  35. 188
  36. 1155
  37. 194
  38. 354
  39. 589
  40. 911

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