The rule was on page 96...clear as mud...and I quote: Any number divided by 0 = 02 ¸ 0 = 0
This will simplify things. It must be true. It's in a published text...even in its Third Edition with a copyright of 1986, so its editors/users have certainly caught any careless errors.
So now I know...Any number divided by 0 = 0. That is, 5 ¸ 0 = 0. This easily memorized rule will make math easy...until that is, I try to check my work (i.e. a ¸ b = c IFF b x c = a). Does 0 x 0 = 5? Must be true. But then because 4 ¸ 0 = 0, we also have 0 x 0 = 4, which then means that 4 = 5 by the transitive property.
In fact, one could proceed to argue that all numbers are equal because of this rule, which makes life very easy. Given any math problem, one could put down any number, and it would be right. Ah, the power of memorized rules!
And, then on page 224, the same book asks what 4! = ?...where it states that one should read 4! = 4 x 3 x 2 x 1 as "four prime."
Oh, and the name of the book with these gems: ARCO's Practice for Army Placement Tests. Its a !book.