Algorithm Factorial

Input: A natural number $n$

Output: $n!$

$(1)$ let $f$:$=1$

$(2)$ repeat

$--($a$)$ let $f$:$=f*n$

$--($b$)$ let $n$:$=n-1$

$(3)$ until $n=0$

$(4)$ return $f$

Now use the algorithm to compute the factorial of $n=4.$

Input: A natural number $n=$

$(1)$ let $f$:$=1.$

$(2)$ repeat

$--($a$)$ let $f$:$=f*n=$

$--($b$)$ let $n$:$=n-1=$

$(3)$ Because the statement $n=1$ is false, the loop is repeated. We continue with step

$(2)$ repeat

$--($a$)$ let $f$:$=f*n=$

$($b$)$ let $n$:$=n-1=47$