10101 x ( 5/10101 - 5/20202 + 5/30303 - 5/40404 ) = 10101 x ( 5/10101 - 5/10101x2 + 5/10101x3 - 5/10101 x 4 )
= 10101 x ( 5/10101 x - 5/10101 x 1/2 + 5/10101 x 1/3 - 5/10101 x 1/4 )
= 10101 x 5/10101 x ( 1 - 1/2 + 1/3 - 1/4 )
= 10101 x 5/10101 x 1 - 7/12
= 10101 x 5/10101 x 3/4
= 10101 x 15/40404
= 151515/40404
= 15/4