（1+1/2+1/3+1/4）乘以（1/2+1/3+1/4+1/5）-（1+1/2+1/3+1/4+1/5）乘以（1/2

=3乘以2乘以1,=4乘以3乘以2乘以1,=5乘以4乘以3乘以2乘以1,那么100!除以99! 1乘以2乘以3乘以4乘以5乘以.100积有几个零 一乘以二乘以三分之一加2乘以3乘以4分之一+3乘以4乘以5分之1+……+48乘以49乘以50分之1. 2乘以1+4乘以3+6乘以5直接加到50乘以49 1乘以2+2乘以3+3乘以4+4乘以5……+97乘以98+98乘以99+99乘以100等于多少 1乘以3分之2乘以4分之3乘以5分之4乘以.乘以20分之19等于多少? 1乘以2乘以3分之1+2乘以3乘以4分之1+3乘以4乘以5分之1+4乘以5乘以6分之1+········+48乘以49乘 1乘以2乘以3乘以4乘以一直乘到100等于多少? 1乘以2乘以3乘以4再乘以几等于100? 观察1乘以2乘以3乘以4+1=25=5² 2乘以3乘以4乘以5+1=121=11² 1除以(1乘以2乘以3)加上1除以(2乘以4乘以3)加上1除以(3乘以4乘以5)加上.1除以(8乘以9乘以10) 1乘以2乘以3分之1加上2乘以3乘以4分之1加上3乘以4乘以5分之1加上.11乘以12乘以13分之1等于多少