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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 918 · 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. 1.908 − 241 =
  2. 2.380 + 423 =
  3. 3.567 − 139 =
  4. 4.388 + 393 =
  5. 5.699 − 555 =
  6. 6.523 + 477 =
  7. 7.163 + 375 =
  8. 8.605 − 453 =
  9. 9.707 + 168 =
  10. 10.650 + 133 =
  11. 11.741 − 425 =
  12. 12.123 + 158 =
  13. 13.692 − 198 =
  14. 14.252 + 475 =
  15. 15.604 − 254 =
  16. 16.393 + 602 =
  17. 17.764 + 422 =
  18. 18.260 + 335 =
  19. 19.439 + 679 =
  20. 20.785 − 607 =
  21. 21.476 − 309 =
  22. 22.465 − 181 =
  23. 23.797 − 328 =
  24. 24.629 + 194 =
  25. 25.555 − 304 =
  26. 26.708 − 355 =
  27. 27.683 − 541 =
  28. 28.676 − 205 =
  29. 29.793 − 199 =
  30. 30.271 + 606 =
  31. 31.572 + 281 =
  32. 32.639 − 323 =
  33. 33.747 − 171 =
  34. 34.227 + 127 =
  35. 35.381 + 634 =
  36. 36.432 + 598 =
  37. 37.348 + 587 =
  38. 38.942 − 275 =
  39. 39.505 − 377 =
  40. 40.888 − 773 =

Answer key

  1. 667
  2. 803
  3. 428
  4. 781
  5. 144
  6. 1000
  7. 538
  8. 152
  9. 875
  10. 783
  11. 316
  12. 281
  13. 494
  14. 727
  15. 350
  16. 995
  17. 1186
  18. 595
  19. 1118
  20. 178
  21. 167
  22. 284
  23. 469
  24. 823
  25. 251
  26. 353
  27. 142
  28. 471
  29. 594
  30. 877
  31. 853
  32. 316
  33. 576
  34. 354
  35. 1015
  36. 1030
  37. 935
  38. 667
  39. 128
  40. 115

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