Răspuns :
N=13+2(1+2+3+.....10+11+12)
se observa ca 1+12=13, 2+11=13, 3+10=13 deci
N=13+2*13*6=13(1+12)=13*13 patrat perfect
se observa ca 1+12=13, 2+11=13, 3+10=13 deci
N=13+2*13*6=13(1+12)=13*13 patrat perfect
N=13+2(1+2+3+.....10+11+12)se observa ca 1+12=13, 2+11=13, 3+10=13 deciN=13+2*13*6=13(1+12)=13*13 patrat perfect