JEE Main 2023 (Online) 13th April Evening ShiftQuestion 1
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
Permutation and Combination
Solution
Alphabetical order: A,D,M,N,O,Y. Words before MONDAY: Start with A or D: $2\cdot5!=240$. Start M, second letter A,D,N (before O): $3\cdot4!=72$. MO, third letter A,D (before N): $2\cdot3!=12$. MON, fourth letter A (before D): $1\cdot2!=2$. MOND then A,Y: MONDAY is first, 0 before. Total before $=240+72+12+2=326$, serial number $=327$. Option C.