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To find the number of cozy 2-digit numbers, we can list all possible cozy numbers that satisfy the condition:
22, 20, 24, 26, 28, 02, 04, 06, 08
Therefore, there are 9 cozy 2-digit numbers.
To find the number of cozy 3-digit numbers, we can use a similar approach. Since the first and last digits of the 3-digit number can be any even digit (0, 2, 4, 6, 8), we only need to consider the middle digit to determine if the number is cozy. There are two cases to consider:
Case 1: The middle digit is even
In this case, we have 5 choices for the first digit (0, 2, 4, 6, 8), and 5 choices for the last digit (0, 2, 4, 6, 8). Therefore, there are 5 x 5 = 25 cozy 3-digit numbers that have an even middle digit.
Case 2: The middle digit is odd
In this case, the middle digit must be next to an even digit, so it must be either 1, 3, 5, or 7. We have 5 choices for the first and last digit (0, 2, 4, 6, 8), and 4 choices for the middle digit. Therefore, there are 5 x 4 x 5 = 100 cozy 3-digit numbers that have an odd middle digit.
Thus, the total number of cozy 3-digit numbers is 25 + 100 = 125.
Therefore, there are 9 cozy 2-digit numbers and 125 cozy 3-digit numbers. you can see also on tutorial CheckMyRota Login