The second number in the given number-pairs is obtained by performing certain mathematical operation(s) on the first number. The same operation(s) are followed in all the number-pairs EXCEPT one. Find that odd number-pair.

9 : 639

THE LOGIC;

1) 4 : 48,

\( {4}^{3} \) - \( {4}^{2} \) = 48

64-16 = 48

2) 6 : 180,

\( {6}^{3} \) - \( {6}^{2} \) = 180

216-36 = 180

3) 8 : 448,

\( {8}^{3} \) - \( {8}^{2} \) = 448

512-64 = 448

4) 9 : 639,

\( {9}^{3} \) - \( {9}^{2} \) = 639

729-81 = 648 not 639

Thus, 9 : 639 is the odd one.