A credit card number has 6 digits (between 1 to 9). The first two digits are 12 in that order, the third digit is bigger than 6, the forth is divisible by 4 and the fifth digit is 3 times the sixth. How many different credit card numbers exist?  Choose the correct choice from the following answers: A) 27 B) 36 C) 72 D) 18 E) 422
{1}{2}{greater than 6}{divisible by 4}{3x}{x}:   The third digit can take 3 values: 7, 8, or 9.   The fourth digit can take 2 values: 4, or 8.   The fifth and sixth digits can take 3 values: 31, 62, or 93.   Total = 3*2*3= 
<gadget id="calculator">3*2*3</gadget>
<output>18</output>
18.   Answer: 18.
<result>D</result>
A credit card number has 6 digits (between 1 to 9). The first two digits are 12 in that order, the third digit is bigger than 6, the forth is divisible by 4 and the fifth digit is 3 times the sixth. How many different credit card numbers exist?