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Question: Answered & Verified by Expert
All words, with or without meaning, are made using all the letters of the word MONDAY. These words are written as in a dictionary with serial numbers. The serial number of the word MONDAY is
MathematicsPermutation CombinationJEE MainJEE Main 2023 (13 Apr Shift 2)
Options:
  • A 327
  • B 328
  • C 324
  • D 326
Solution:
1023 Upvotes Verified Answer
The correct answer is: 327

The given word is MONDAY

Arranging the letters alphabetically, we get

ADMNOY

When the word starts with any of the letters A/D, the number of possibilities=5!×2=240

Now when the word starts with MA, then the number of possibilities=4!=24

Now when the word starts with MD, then the number of possibilities =4!=24

Now when the word starts with MN, then the number of possibilities =4!=24

Now when the word starts with MOA, then the number of possibilities=3!=6

Now when the word starts with MOD, then the number of possibilities =3!=6

Now when the word starts with MONA, then the number of possibilities =2!=2

Now when the word starts with MONDAY, then the number of possibilities=1

Rank =240+24×3+6×2+2+1=327

Hence, rank of the word MONDAY is 327.

SHORTCUT METHOD

Another method is a shortcut, first number the alphabet and then check how many number are there on right hand side less that number and then start number in factorial in decreasing order and then multiply and add them and in last add one to find rank, 

354216MONDAY2321005!4!3!2!1!0!

 Rank =(2×5!+3×4!+2×3!+1×2!)

=240+72+12+2+1=327

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