=>1/100 - 1/100.99 - 1/99.98 - 1/98.97 - ... - 1/3.2 - 1/2.1
=>1/100 - ( 1/100.99 + 1/99.98 + 1/98.97 + ... + 1/3.2 + 1/2.1)
=>1/100 - ( 1/1.2 + 1/2.3 + ... + 1/97.98 + 1/98.99 + 1/99.100)
=>1/100 - ( 1 - 1/100)
=>1/100 - 99/100
=>-98/100 = -49/50
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