Question

1) (i)

How can you tell that 56290040037 is a valid identification number of an American Express Travelers Cheque?

	a) The sum of the digits is an even number.
	b) The number ends in a 7.
	c) The sum of the digits is divisible by 9.

(ii)

The ZIP + 4 code consists of nine digits and a check digit. How do you verify that a given code is a valid ZIP + 4 code?

	a) Three times the sum of the odd-positioned digits plus the remaining digits is divisible by 11.
	b) The actual number is divisible by 10.
	c) The sum of the 10 digits is divisible by 10.

(iii).

Prior to June 25, 2011, what did the first three digits of a Social Security number indicate?

	a) They indicate where the recipient was born.
	b) They indicate the age of the recipient at the time it was applied for.
	c) They indicate where the card was applied for.

Please answer in detail and explain well each question.

Answer 1

1) The sum of digits is divisible by 9 (this is the criteria used by AMEX for its CC check digit)

2) Three times the sum of the odd-positioned digits plus the remaining digits is divisible by 11.

Again, this is the criteria for the check-digit given a 9 digit ZIP+4 code

3) The first three digit encode the area number where the application was received from. Correct option is C)

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