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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 951 · 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. 1.214 + 523 =
  2. 2.558 + 182 =
  3. 3.810 − 395 =
  4. 4.370 + 221 =
  5. 5.679 + 366 =
  6. 6.542 − 232 =
  7. 7.820 − 577 =
  8. 8.834 − 431 =
  9. 9.226 + 599 =
  10. 10.466 + 274 =
  11. 11.491 + 371 =
  12. 12.135 + 452 =
  13. 13.684 + 616 =
  14. 14.126 + 635 =
  15. 15.125 + 627 =
  16. 16.718 + 223 =
  17. 17.149 + 575 =
  18. 18.433 + 304 =
  19. 19.671 − 413 =
  20. 20.648 + 389 =
  21. 21.326 + 251 =
  22. 22.849 − 245 =
  23. 23.581 + 689 =
  24. 24.279 + 689 =
  25. 25.818 − 274 =
  26. 26.482 − 367 =
  27. 27.700 + 485 =
  28. 28.482 − 161 =
  29. 29.176 + 365 =
  30. 30.423 + 536 =
  31. 31.475 − 249 =
  32. 32.212 + 218 =
  33. 33.214 + 651 =
  34. 34.435 − 284 =
  35. 35.744 − 442 =
  36. 36.527 − 129 =
  37. 37.685 + 141 =
  38. 38.525 + 293 =
  39. 39.395 + 275 =
  40. 40.734 − 301 =

Answer key

  1. 737
  2. 740
  3. 415
  4. 591
  5. 1045
  6. 310
  7. 243
  8. 403
  9. 825
  10. 740
  11. 862
  12. 587
  13. 1300
  14. 761
  15. 752
  16. 941
  17. 724
  18. 737
  19. 258
  20. 1037
  21. 577
  22. 604
  23. 1270
  24. 968
  25. 544
  26. 115
  27. 1185
  28. 321
  29. 541
  30. 959
  31. 226
  32. 430
  33. 865
  34. 151
  35. 302
  36. 398
  37. 826
  38. 818
  39. 670
  40. 433

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