(51+三十五分之三十四)除以17 19.9+19.9乘99 999乘1999简算

(51+34/35)÷17
=(51+34/35)*1/17
=51*1/17 +34/35*1/17
=3+2/35
=3又2/25
19.9+19.9*99
=19.9*(1+99)
=19.9*100
=1990
999*1999
=(1000-1)*1999
=1999000-1999
=1999000-(2000-1)
=1999000-2000+1
=1997000+1
=1997001