Question

Write all possible $3-\mathrm{digit}$ numbers that can be formed by the digits $1,3$ and $7$, using each digit only once in each number.

Answer 1

Here we have to form $3-\mathrm{digit}$ numbers using digits $1,3$ and $7$ using each digit only once in each number

Keeping $1$ at ones place, $3-\mathrm{digit}$ numbers are $371\mathrm{and}731$

Keeping $3$ at ones place, $3-\mathrm{digit}$ numbers are $173\mathrm{and}713$

Keeping $7$ at ones place, $3-\mathrm{digit}$ numbers are $137\mathrm{and}317$

Hence the required numbers are $371,731,173,713,137$ and $317$