From a typo, I stumbled across one of the math identifiers that returns a value in spite of having a missing parm. And from there I found that it's not alone. These are all supposed to have 2 parameters, but when only 1 parm is used they return the parm1 number instead of the 'too few parameters' error:
//echo -a $and(123)
//echo -a $bitoff(123)
//echo -a $biton(123)
//echo -a $isbit(123) returns 0
//echo -a $or(123)
//echo -a $xor(123)
//echo -a $round(123.456)
