$$\frac{{4.2 \times 4.2 - 1.9 \times 1.9}}{{2.3 \times 6.1}}$$    is equal to:

Solution (By Examveda Team)

$$\eqalign{ & \text{Let } a = 4.2 \text{ and } b = 1.9 \cr & {\text{Given Expression}} \cr & = \frac{{ {{a^2} - {b^2}} }}{{\left( {a + b} \right)\left( {a - b} \right)}} \cr & = \frac{{ {{a^2} - {b^2}} }}{{ {{a^2} - {b^2}} }} \cr & = 1 \cr} $$