x:7=c1 rest 6
x=M₇+6
x=abc cu bara deasupra
x=10*7+6=70+6=76 nu apartine conditiei
x=11*7+6=77+6=83 nu apartine conditiei
x=12*7+6=84+6=90 nu apartine conditiei
x=13*7+6=91+6=97 nu apartine conditiei
x=14*7+6=98+6=104
x=15*7+6=105+6=111
.......................................
x=141*7+6=9987+6=993
141-13=128 numere naturale de 3 cifre ce indeplinesc conditia data
