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1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20=​

Răspuns :

•sau poti folosi suma lui gauss

FORMULA:

☆n(n+1)/2☆

•n fiind ultimul nr

REZOLVARE:

(20+1)/2=20×21/2=420/2=210