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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 897 · 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. 1.500 + 283 =
  2. 2.496 − 151 =
  3. 3.513 + 534 =
  4. 4.550 − 445 =
  5. 5.429 − 116 =
  6. 6.636 − 536 =
  7. 7.238 + 431 =
  8. 8.694 − 391 =
  9. 9.908 − 646 =
  10. 10.571 + 368 =
  11. 11.613 + 588 =
  12. 12.726 + 478 =
  13. 13.499 + 611 =
  14. 14.145 + 532 =
  15. 15.709 + 286 =
  16. 16.139 + 198 =
  17. 17.562 + 136 =
  18. 18.827 − 146 =
  19. 19.620 − 193 =
  20. 20.575 + 468 =
  21. 21.705 + 543 =
  22. 22.722 + 506 =
  23. 23.543 + 248 =
  24. 24.771 + 602 =
  25. 25.295 + 625 =
  26. 26.292 + 344 =
  27. 27.605 + 175 =
  28. 28.956 − 683 =
  29. 29.963 − 859 =
  30. 30.665 − 126 =
  31. 31.858 − 198 =
  32. 32.646 − 218 =
  33. 33.383 + 579 =
  34. 34.730 − 514 =
  35. 35.483 − 211 =
  36. 36.124 + 567 =
  37. 37.493 + 249 =
  38. 38.572 − 276 =
  39. 39.519 + 424 =
  40. 40.658 − 128 =

Answer key

  1. 783
  2. 345
  3. 1047
  4. 105
  5. 313
  6. 100
  7. 669
  8. 303
  9. 262
  10. 939
  11. 1201
  12. 1204
  13. 1110
  14. 677
  15. 995
  16. 337
  17. 698
  18. 681
  19. 427
  20. 1043
  21. 1248
  22. 1228
  23. 791
  24. 1373
  25. 920
  26. 636
  27. 780
  28. 273
  29. 104
  30. 539
  31. 660
  32. 428
  33. 962
  34. 216
  35. 272
  36. 691
  37. 742
  38. 296
  39. 943
  40. 530

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