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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 865 · 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. 1.669 + 582 =
  2. 2.341 + 212 =
  3. 3.422 − 183 =
  4. 4.189 + 124 =
  5. 5.291 + 174 =
  6. 6.507 − 406 =
  7. 7.534 + 328 =
  8. 8.950 − 262 =
  9. 9.197 + 191 =
  10. 10.781 − 144 =
  11. 11.337 + 385 =
  12. 12.547 − 356 =
  13. 13.734 + 491 =
  14. 14.220 + 301 =
  15. 15.780 + 541 =
  16. 16.464 + 372 =
  17. 17.588 − 263 =
  18. 18.398 + 314 =
  19. 19.796 − 573 =
  20. 20.489 − 171 =
  21. 21.555 − 136 =
  22. 22.555 − 401 =
  23. 23.790 − 596 =
  24. 24.236 + 261 =
  25. 25.618 − 361 =
  26. 26.210 + 669 =
  27. 27.551 + 358 =
  28. 28.175 + 637 =
  29. 29.451 + 616 =
  30. 30.424 + 331 =
  31. 31.430 + 307 =
  32. 32.664 − 533 =
  33. 33.584 − 372 =
  34. 34.451 − 131 =
  35. 35.571 + 431 =
  36. 36.698 − 199 =
  37. 37.611 + 571 =
  38. 38.640 − 411 =
  39. 39.630 + 356 =
  40. 40.954 − 469 =

Answer key

  1. 1251
  2. 553
  3. 239
  4. 313
  5. 465
  6. 101
  7. 862
  8. 688
  9. 388
  10. 637
  11. 722
  12. 191
  13. 1225
  14. 521
  15. 1321
  16. 836
  17. 325
  18. 712
  19. 223
  20. 318
  21. 419
  22. 154
  23. 194
  24. 497
  25. 257
  26. 879
  27. 909
  28. 812
  29. 1067
  30. 755
  31. 737
  32. 131
  33. 212
  34. 320
  35. 1002
  36. 499
  37. 1182
  38. 229
  39. 986
  40. 485

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