Răspuns :
(1x4+2x4+...+13×4)
4x(1+2+3...+13)
4x(13×14:2)
4x13x7
364
(2-6...-50)
52-(2×1+2×3+...2×25)
52-2×{(26×27:2)}:2
13×27
351
364-351=13
Rasp final 13
4+8+12+16+20+24+28+32+36+40+44+48+52-2-6-10-14-18-22-26-30-34-38-42-46-50=26