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)

$3999960$

Answer 2

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 $= 360 \times 10000 + 360 \times 1000 + 360 \times 100 + 360 \times 10 + 360$ $= 3999960$.