**Excercise 2.**
This software checks the validity of a UPC number. Use it to verify that 090146003386 is valid. Now enter the same number with one digit incorrect. Was the error detected? Enter the number with two consecutive digits transposed. Was the error detected? Enter the number with the 3 and the 8 transposed. Was the error detected? Explain why or why not. Enter the number with the 9 and the 1 transposed. Was the error detected? Explain why it was or was not.

Please enter 12-digits UPC or the first 11 digits of the
number here: