Răspuns :
5!=1*2*3*4*5=120
6!*13-5!*12=5!(6*13-12)=5!(78-12)=5!*66=120*66=7920
6!*13-5!*12=5!(6*13-12)=5!(78-12)=5!*66=120*66=7920
5!(6 x 13 - 12)=5! x 66=1 x 2 x 3 x 4 x 5 x 66=7920
remember!
n!=1x2x3x4x5x.........xn
remember!
n!=1x2x3x4x5x.........xn