a=3*(1+11+...+1111..1)
=3*[(10-1)+(100-1)+...+(1000...-1)]÷9
=(10+100+..+10^2013+2013)÷3
=1111.10(2013个1)÷3+671
=370370...370(671个370)+671
数字和为:
(3+7)×671+6+7+1=6724
a=3*(1+11+...+1111..1)
=3*[(10-1)+(100-1)+...+(1000...-1)]÷9
=(10+100+..+10^2013+2013)÷3
=1111.10(2013个1)÷3+671
=370370...370(671个370)+671
数字和为:
(3+7)×671+6+7+1=6724