Find the difference between the banker's discount and the true discount on Rs. 8100 for 3 months at 5%?

Difference between banker's discount and the true discount = Banker's gain.
⇒ B.G. = (B.D.) - (T.D.)
B.D. = FTR / 100
= [8100 x (1/4) x 5] / 100
= 101.25
T.D. = FTR / (100 + TR)
= [8100 x (1/4) x 5] / (100 + 5/4)
= 100
⇒ B.G. = 101.25 - 100
= Rs. 1.25