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```
# A ruby program to find factorial of a given integer
# Factorial of a given integer is defined as the product of all the positive integers less than or equal to the given integer
# Mathematical representation: n! = n * (n - 1) * (n - 2) * ... * 1
#
# Non-recursive and non-iterative approach
#
def factorial(number)
if number < 0
'Please check your input number! The given number is a negative number.'
elsif number == 0
"The factorial of #{number} is 1."
else
result = (1..number).inject(:*)
"The factorial of #{number} is #{result}."
end
rescue StandardError
'Error: Please provide integer only!'
end
# Valid inputs
puts factorial(0)
# The factorial of 0 is 1.
puts factorial(4)
# The factorial of 4 is 24.
puts factorial(10)
# The factorial of 10 is 3628800.
puts factorial(1)
# The factorial of 1 is 1.
puts factorial(-5)
# Please check your input number! The given number is a negative number.
# Invalid inputs
puts factorial('a')
# Error: Please provide integer only!
puts factorial('2')
# Error: Please provide integer only!
```