Question

The sum of all the five digit numbers formed with the digits $1,2,3,4,5$ taken all at a time, is

• A. $15(5!)$
• B. $3999960$
• C. $3990000$
• D. None of these

Answer 1

Answer: (B)

Sum of unit's place $=4!(1+2+3+4+5)$
$=24\times 15=360$
[Since $1$ will come $24$ times in unit place and so the other digits if $5$ digit number is formed with digits $1,2,3,4,5$ taken all at a time]
So the sum in tens, hundreds, thousands and ten thousands places is $=360\times 10000+360\times 1000+360\times 100+360\times 10+360$
$=3999960$.