Question

How many $10-digit$ numbers can be formed by using the digits $1$ and $2$?

• A. ${}^{10}{P}_2$
• B. ${}^{10}{C}_2$
• C. $2^{10}$
• D. $10!$

Answer 1

The correct option is C $2^{10}$

Each place of a ten digit number can be fixed by any of the two digits. So, the number of ways to form a ten digit number is $2^{10}$.