Choose the number that is different from the others in the group.

In this type of odd-one-out problem, every number in the group is built using the same digit rule, and the one number that breaks that rule is the answer. Here, check whether the middle digit of each three-digit number equals the product of its first and last digits.

1. 263: first digit x last digit = 2 x 3 = 6, which equals the middle digit 6, so it follows the rule.

2. 242: first digit x last digit = 2 x 2 = 4, which equals the middle digit 4, so it follows the rule.

3. 551: first digit x last digit = 5 x 1 = 5, which equals the middle digit 5, so it follows the rule.

4. 383: first digit x last digit = 3 x 3 = 9, but the middle digit shown is 8 (not 9), so it breaks the rule.

Three of the four numbers, 263, 242 and 551, satisfy the rule that the middle digit equals the product of the first and last digits, while 383 does not.

Therefore, 383 is the number that is different from the others in the group.