_magMul10Add
private fn
void _magMul10Add(ref ubyte[16] mag, int digit) @safe pureMultiplies a magnitude by 10 and adds one digit (0..9); overflow throws.
void _magMul10Add(ref ubyte[16] mag, int digit) @safe pureMultiplies a magnitude by 10 and adds one digit (0..9); overflow throws.