The sum of the digits in the unit's place of all the 4 - digit numbers formed by using the numbers 3 ,   4 ,   5 and   6 , without repetition is :

Question

The sum of the digits in the unit's place of all the 4 - digit numbers formed by using the numbers 3 , &#160; 4 , &#160; 5 and &#160; 6 , without repetition is :

Aicharya · Accepted Answer

By fixing one digit at unit place we can form toal number without repetition is $3!$

Sum of digits $= 3! . (6 + 5 + 4 + 3)$

$= (6) (18) = 108$ $\{∵ n! = n . (n - 1) . . . 3.2.1\}$

The sum of the digits in the unit's place of all the 4 - digit numbers formed by using the numbers 3 ,…

Solution

The sum of the digits in the unit&#39;s place of all the 4 - digit numbers formed by using the numbers 3 ,…

Solution

The sum of the digits in the unit's place of all the 4 - digit numbers formed by using the numbers 3 ,…