Question

The sum of all the numbers which can be formed by using $1,3,5,7$ all at a time and which have no digit repeated is

Answer 1

$1,3,5$ and $7$ digits are formed

If digits are not repeated then number of ways$=4\times 3\times 2\times 1=24ways$

Sum at unit place $\frac{24}{6}(1+3+5+7)=6\left(16\right)=96$

So, sum $=96+96\times 10+96\times 100+96\times 1000=106656$

Answer