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

Three of the following four options are alike in a certain way and thus form a group. Which is the option that does NOT belong to that group?

Four triads of numbers have been given out of which three are alike in some manner and one is different. Select the one that is different.

Which roll number is a perfect cube?

Three of the following four are alike in a certain way and thus form a group. Which is the one that does NOT belong to that group?
NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g. 13 - Operations on 13 such as adding/deleting/ multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed)
(A) 56-7
(B) 169-13
(C) 729-27
(D) 121-11

Three of the following number-pairs are alike in some manner and hence form a group.
Which number-pair does not belong to that group?
(NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g. 13 - Operations on 13 such as adding/subtracting/ multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed.)

Four number-pairs are given, three follow a pattern. Choose the odd pair.