Here is a good idea, I think

[Guy.Steele at CMU-10A]

Presumably (EVENP x y)  <=>  (ZEROP (MOD x y)) ?

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Mail-From: ARPANET host PARC-MAXC received by CMU-10A at 14-Oct-82 20:51:44-EDT
Date: Thu, 14 Oct 1982 21:52:00 -0000
From: Masinter at PARC-MAXC
Subject: optional argument for EVENP?
To: Guy.Steele@CMU-10A
cc: , Masinter.PA

We've found a need in our system for two-argument EVENP, 

(EVENP n &optional divisor)
	divisor defaults to 2. Predicate returns true if n is an integral multiple
	of divisor.

(ODDP n &optional divisor) is merely (NOT (EVENP n divisor)).

This seems to be a logical extension of MOD.
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