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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 887 · 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. 1.495 − 297 =
  2. 2.955 − 821 =
  3. 3.777 + 248 =
  4. 4.687 + 371 =
  5. 5.591 − 163 =
  6. 6.490 + 226 =
  7. 7.240 + 141 =
  8. 8.649 − 461 =
  9. 9.200 + 647 =
  10. 10.332 + 366 =
  11. 11.544 + 487 =
  12. 12.654 − 118 =
  13. 13.707 − 575 =
  14. 14.192 + 371 =
  15. 15.590 − 421 =
  16. 16.321 + 435 =
  17. 17.791 − 112 =
  18. 18.454 + 605 =
  19. 19.780 + 407 =
  20. 20.703 + 226 =
  21. 21.899 − 349 =
  22. 22.270 + 133 =
  23. 23.568 + 661 =
  24. 24.642 + 536 =
  25. 25.791 − 247 =
  26. 26.563 + 633 =
  27. 27.627 − 294 =
  28. 28.211 + 405 =
  29. 29.721 − 181 =
  30. 30.165 + 354 =
  31. 31.957 − 352 =
  32. 32.667 + 541 =
  33. 33.735 − 278 =
  34. 34.250 + 323 =
  35. 35.588 + 161 =
  36. 36.485 + 165 =
  37. 37.702 − 481 =
  38. 38.924 − 411 =
  39. 39.712 − 501 =
  40. 40.563 + 681 =

Answer key

  1. 198
  2. 134
  3. 1025
  4. 1058
  5. 428
  6. 716
  7. 381
  8. 188
  9. 847
  10. 698
  11. 1031
  12. 536
  13. 132
  14. 563
  15. 169
  16. 756
  17. 679
  18. 1059
  19. 1187
  20. 929
  21. 550
  22. 403
  23. 1229
  24. 1178
  25. 544
  26. 1196
  27. 333
  28. 616
  29. 540
  30. 519
  31. 605
  32. 1208
  33. 457
  34. 573
  35. 749
  36. 650
  37. 221
  38. 513
  39. 211
  40. 1244

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