100^k/(2*(2k-1))*(5^(2k-2))=
100*k/((2^2k)2^(-1))((5^2k)*5^(-2))=
50*100^k/2^2k*5^2k=50*100^k/(2*5)^2k=50*100^k/10^2k=50*100^k/(10^2)^k=50*100^k/100^k=50
100^k/(2*(2k-1))*(5^(2k-2))=
100*k/((2^2k)2^(-1))((5^2k)*5^(-2))=
50*100^k/2^2k*5^2k=50*100^k/(2*5)^2k=50*100^k/10^2k=50*100^k/(10^2)^k=50*100^k/100^k=50