Question

The total number of natural numbers of $6$ digits that can be made with digits $1,2,3,4$, where all the digits are to appear in the same number at least once, is

• A. 1560
• B. 840
• C. 1080
• D. 480

Answer 1

The correct option is A 1560

We need to form a $6$ digits numbers by using digits $1,2,3,4$.

Hence, total number of $6$ digit numbers $=\frac{{}^4{C}_2\cdot 6!}{2!2!}+\frac{{}^4{C}_1\cdot 6!}{3!}=5!\times 13=1560$