Question

How Do You Do This Sum Quickly?
9,950 x 10,050 = ?

Answer 1

Dear student
$$\begin{gathered} 9950\times 10050 \\ =\left(10000-50\right)\times \left(10000+50\right) \\ ={10000}^2-{50}^2\left[x^2-y^2=\left(x-y\right)\left(x+y\right)\right] \\ =100000000-2500 \\ =99997500 \end{gathered}$$
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