12+56+1112+1920+2930+…+97019702+98999900
12+56+1112+1920+2930+…+97019702+98999900
12+56+1112+1920+…+379380
找规律:56 1112 1920
12,34,56,78,910,1112……第20个数是( )
1+12+23+34+45+56+67+78+89+910+1011+1112+1213+1314+1415+1516+
12,1112,3122,211213,()
(1112
求-1/1011-1/1112-1/1213...1/1920的值
数字推理 12,1112,3112,211213,
数列12 ,121 ,1112,(),201121,4022000
12×34×56×78×…×99100
用11到2011这些自然数依次组成下列算式:1112 1314,1516 1718,1920 2122,2324 252