Home > Practice > Arithmetic Aptitude > Permutations and Combinations > Miscellaneous
1. How many positive integers 'n' can be form using the digits 3, 4, 4, 5, 6, 6, 7 if we want 'n' to exceed 60,00,000?
If the first digit is 6, the other digits can be arranged in = 360 ways.
If the first digit is 7, the other digits can be arranged in = 180 ways.
Thus required possibilities for n,
= 360 + 180
= 540 ways
Solution:
As per the given condition, number in the highest position should be either 6 or 7, which can be done in 2 ways.If the first digit is 6, the other digits can be arranged in = 360 ways.
If the first digit is 7, the other digits can be arranged in = 180 ways.
Thus required possibilities for n,
= 360 + 180
= 540 ways