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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 545 · 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. 1.485 + 306 =
  2. 2.193 + 185 =
  3. 3.458 + 645 =
  4. 4.396 + 246 =
  5. 5.330 + 432 =
  6. 6.717 − 261 =
  7. 7.698 + 582 =
  8. 8.697 + 209 =
  9. 9.843 − 154 =
  10. 10.475 + 505 =
  11. 11.515 − 261 =
  12. 12.657 + 544 =
  13. 13.538 − 251 =
  14. 14.699 + 402 =
  15. 15.640 + 503 =
  16. 16.422 − 236 =
  17. 17.170 + 391 =
  18. 18.632 + 191 =
  19. 19.949 − 191 =
  20. 20.594 − 409 =
  21. 21.352 + 216 =
  22. 22.483 + 334 =
  23. 23.582 + 187 =
  24. 24.405 + 136 =
  25. 25.472 + 138 =
  26. 26.399 + 174 =
  27. 27.522 − 268 =
  28. 28.210 + 604 =
  29. 29.392 + 529 =
  30. 30.305 + 301 =
  31. 31.191 + 246 =
  32. 32.856 − 391 =
  33. 33.249 + 145 =
  34. 34.663 − 181 =
  35. 35.493 + 303 =
  36. 36.654 + 579 =
  37. 37.604 + 427 =
  38. 38.870 − 314 =
  39. 39.851 − 267 =
  40. 40.361 + 394 =

Answer key

  1. 791
  2. 378
  3. 1103
  4. 642
  5. 762
  6. 456
  7. 1280
  8. 906
  9. 689
  10. 980
  11. 254
  12. 1201
  13. 287
  14. 1101
  15. 1143
  16. 186
  17. 561
  18. 823
  19. 758
  20. 185
  21. 568
  22. 817
  23. 769
  24. 541
  25. 610
  26. 573
  27. 254
  28. 814
  29. 921
  30. 606
  31. 437
  32. 465
  33. 394
  34. 482
  35. 796
  36. 1233
  37. 1031
  38. 556
  39. 584
  40. 755

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