Question
Mathematics Question on permutations and combinations
Using the number 1, 2, 3 ... 7, total numbers of 7 digit number which does not contain string 154 or 2367 is (Repetition is not allowed)
A
4897
B
4898
C
4896
D
4899
Answer
4898
Explanation
Solution
The correct option is (B): 4898
Total numbers - when 154 comes as a n string-when 2367 comes as+2 a string
7!-5!-4!+2
5040-120-24+2
=4898