Correct answers only !
credit cards have 16 digit numbers, of which the first 15 digits identify the credit card and the sixteenth digit is the check digit (the last digit is fixed). u-kan-trust-us credit card numbers begin with 61, 62, or 63. what is the maximum number of credit cards that uktu can issue?
a. 3 ( 10^12)
b. 3 (10^13)
c. 3 (10^14)
d. 3 (10^15)

  B.  3×10^13

Step-by-step explanation:

The first two digits are fixed at one of three pairs of values; the last digit is "fixed" as the check digit, leaving 16 - 3 = 13 free digits. These can take on any of 10^13 values.

The total number of possible card numbers is 3×10^13.

The correct option is B.

Step-by-step explanation:

Total possible digits are 0,1,2,3,4,5,6,7,8,9.

Total number of digits in a credit card = 16

It is given that that the last digit of credit card is fixed.

Total number of possible ways for 16th digit = 1

U-Kan-Trust-Us Credit Card numbers begin with 61, 62, or 63.

Total number of possible ways for first two digits = 3

Remaining places = 16 - 1 - 2 = 13

In these 13 remaining places any of 10 digits can be occur.

Total number of possible ways for remaining 13 digits =

The maximum number of credit cards that UKTU can issue is

Therefore the correct option is B.

a is the right answer