How many 4-digit numbers are there if no digit is repeated?
Or
How many numbers are there between 1000 and 9999 so that no digit is repeated?
Number of letters in word 'MONDAY' = 6 (all district)
Number of vowels = 2 (O and A)
Number of letters to be used in 4 and first letter is a vowel,
Number of arrangements for box 1 = (i)
(Two vowels for 1 box)
We now have 5 letters left and 3 boxes for them.
n = 5, r = 3
∴ The number of permutations ...(ii)
Hence, from (i) and (ii), the total number of permutations i.e., the number of words formed:
= 2 x 60 = 120.
How many words, with or without meaning, can be formed using all the letters of the word EQUATION at a time so that the vowels and consonants occur together?
How many words, with or without meaning, can be formed using all the letters of the word EQUATION at a time so that no two consonants are together.