What is (2 + 4 + 6 + 8 + ····· + 100) - (1 + 3 + 5 + 7 + ······ + 99) equal to

What is (2 + 4 + 6 + 8 + ····· + 100) - (1 + 3 + 5 + 7 + ······ + 99) equal to

=(2-1)+(4-3)+…… +(100-99)
=1+1+…… +1
=1×50
=50