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Fie n=1223334444...99...9...2020...20
Calculați suma cifrelor lui n


Răspuns :

n=1223334444...99...9...2020...20 =
=1+2*2+3*3+4*4+.....+9*9+....+20*20=
=1+4+9+16+25+36+49+64+81+100+121+144+169+196+225+256+289+324+
+361+400=2870