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 7, the forth is divisible by 3 and the fifth digit is 3 times the sixth. How many different credit card numbers exist? Choices.
A) 18	B) 36	C) 72	D) 112	E) 422
{1}{2}{greater than 7}{divisible by 3}{3x}{x}:   The third digit can take 2 values: 8, or 9.   The fourth digit can take 3 values: 3, 6, or 9.   The fifth and sixth digits can take 3 values: 31, 62, or 93.   Total = 2*3*3= 
<gadget id="calculator">2*3*3</gadget>
<output>18</output>
18.   18nswer: 18.
<result>A</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 7, the forth is divisible by 3 and the fifth digit is 3 times the sixth. How many different credit card numbers exist?