247<ab+ ab+2 + ab+4 +cde+ cde+2<255
b=cifra para; e=cifra impara
247<3•ab+2•cde+8<255
239<3ab+2cde<247; 3ab+2cde= numar par
3ab+2cde∈{240; 242, 244; 246}
30≤3ab≤42; si 202≤2cde ≤246
ab=10 => 2cde ∈{210; 212; 214; 216}, dar e=cifra impara
=> ab=10 si cde ∈{105; 107}
=> 10+12+14+105+107=248; 247<248<255
sau 10+12+14+107+109=252; 247<252<255
ab=12 => 3ab=36 si 2cde ∈ {204, 206, 208, 210} si e=cifra impara
ab=12 si cde ∈{103, 105}
=> 12+14+16+103+105=250; 247<250<255
sau 12+14+16+105+107=254; 247<254<255
ab=14 => 3ab=42 si 2cde ∈ {198; 200; 202; 204};
convine doar cde=101
=> 14+16+18+101+103=252; 247<252<255
