Explanation

Reason:

Alternatively, if focusing on divisibility:

Verification:

Thus, 64 is different based on both criteria.

Odd One Out: 64

64 is a perfect square ($8^2 = 64$), while the other numbers (60, 48, 42) are not perfect squares.

64 is not divisible by 3, whereas 60, 48, and 42 are all divisible by 3.

$60÷3=20$ (Divisible by 3)$$60÷3=20(Divisible by 3)

$48 div 3 = 16$ (Divisible by 3)

$42÷3=14$ (Divisible by 3)

$64÷3=21.33$ (Not divisible by 3)