100:121:144:?

What should come in the place of question mark (?) in the following alpha-numeric series? T49S64 , R81Q100,P121O144, ?

[(sqrt(81-:25)-sqrt(144-:121))-:sqrt(1521-:484)]=?

The tens digit of (81)^(100)(121)^(100)-1 is

The tens digit of (81)^(100)(121)^(100)-1 is

The sequence 10000, 121, 100, 31, 24, ?, 20 represent a number x with respect to different bases. The missing number in this sequence is

In each of the following questions select the missing number from the given responses. {:(2,3,4,?),(3,1,4,2),(4,2,2,6),(5,5,2,2),(196,121,144,225):}

Using the square root (sqrt(" ")) , write the squre root of the following squares. (11/12)^(2)=121/144

1.44 =