=( 10* 12)/ 1 1? *( 1 1* 13)/ 12? *...*(98* 100)/99

=( 10* 100)/( 1 1*99)

Formula: (a? - 1)=(a- 1)*(a+ 10)

Topic 2: (1+1/2) * (1-1/2) * (1+1/3) * (1-/kloc)

=3/2* 1/2*4/3*2/3*...* 100/99*98/99

=3/2*2/3*4/3*...*98/99* 100/99* 1/2

= 100/99* 1/2

=50/99

Change the location of each item.

Topic 3: (1+1/2)+(1+1/(1+2))+(1+1)

= 1/2+2*( 1/2- 1/3+ 1/3- 1/4+...+ 1/ 100- 1/ 10 1)+ 100

= 1/2+ 198/202+ 100

=20499/202

A single one has 100, and the remaining numerator denominator *2 is split again.