Drooyan, Irving. <br/><br/>
A programmed introduction to number systems 
/ Irving Drooyan [and] Walter Hadel. 
 - 2nd ed. 
 - New York :  Wiley,  1973 
 - xii, 283 p.  illus., forms.  23 cm. 
<br/><br/> includes bibliography and index<br/> 
<br/><br/>1.	Preliminary concepts<br/>2.	The set of whole numbers<br/>3.	The set of integers<br/>4.	The set of rational numbers <br/>5.	The set of real numbers<br/> 
<br/><br/><label>ISBN: </label>0471222666 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Number theory--Programmed instruction.
<br/><br/><label>Dewey Class. No.: </label>512/.7/077  / D786