nawk ' BEGIN {
	printf("Enter number: ")
}
$1 ~ /[0-9]+/ { 
	number = $1
	fact = number
	for (x = number - 1 ; x > 1; x--)
		fact *= x
	printf("The factorial of %d is %g\n", number, fact)
	exit
}
$1 !~ /[0-9]+/ { printf("\nInvalid entry. Enter a number: ") }' -
#
# A repetitive (not recursive) computation of factotials
#