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Fie A=9+99+999+9999+.....+999.......99999. 999.......99999=2003 cifre
Cate cifre de 1 are numarul A?
a)2007
b)2005
c)1002
d)998
e)Alt raspuns


Răspuns :

cifra unit are 9*2003
zecilor are 9*2002
sutelor are 9* 2001
.
.
.2003 are 9
9*2003+9*2002*10+9*2001*100...+9*2000*1000
18027+180180+1800900+18000000 ... banuiesc ca sunt 1002