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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 976 · 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. 1.788 + 148 =
  2. 2.607 − 275 =
  3. 3.273 + 171 =
  4. 4.610 + 169 =
  5. 5.740 + 304 =
  6. 6.973 − 274 =
  7. 7.689 + 161 =
  8. 8.583 + 252 =
  9. 9.488 + 145 =
  10. 10.655 + 412 =
  11. 11.636 + 475 =
  12. 12.191 + 277 =
  13. 13.551 + 116 =
  14. 14.736 − 112 =
  15. 15.305 + 622 =
  16. 16.778 + 417 =
  17. 17.335 + 296 =
  18. 18.965 − 491 =
  19. 19.729 − 463 =
  20. 20.208 + 653 =
  21. 21.810 − 168 =
  22. 22.332 + 463 =
  23. 23.670 − 247 =
  24. 24.208 + 143 =
  25. 25.547 + 631 =
  26. 26.730 + 522 =
  27. 27.767 + 306 =
  28. 28.140 + 181 =
  29. 29.591 + 206 =
  30. 30.413 − 243 =
  31. 31.501 + 594 =
  32. 32.432 − 264 =
  33. 33.822 − 213 =
  34. 34.660 + 461 =
  35. 35.647 + 524 =
  36. 36.506 − 291 =
  37. 37.720 − 388 =
  38. 38.897 − 651 =
  39. 39.396 + 661 =
  40. 40.666 − 459 =

Answer key

  1. 936
  2. 332
  3. 444
  4. 779
  5. 1044
  6. 699
  7. 850
  8. 835
  9. 633
  10. 1067
  11. 1111
  12. 468
  13. 667
  14. 624
  15. 927
  16. 1195
  17. 631
  18. 474
  19. 266
  20. 861
  21. 642
  22. 795
  23. 423
  24. 351
  25. 1178
  26. 1252
  27. 1073
  28. 321
  29. 797
  30. 170
  31. 1095
  32. 168
  33. 609
  34. 1121
  35. 1171
  36. 215
  37. 332
  38. 246
  39. 1057
  40. 207

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