98!/100!-92 * 112=
=1*2*3*4*...*97*98/[1*2*3*48*...*97*98*99*100]-(99)^2=
=1/9900-(100-1)^2=
=1/9900-[10000-200+1]=
=1/9900-9801.
1/9900-9801=
=(1-9801*9900)/9900=
=[1-9801(10000-100)]/9900=
=[1-98010000-980100]/9900=
=[1-98990100]/9900=
=-98990099/9900=
=-9998又9899/9900【负9998又9900分之9899】.