Think like a Maths genius:  The art of calculating in your head/ 
Arthur Benjamin and Michael Shermer 
 - UK:  Souvenir press,  c2006 
 - xxii, 273p.; 
<br/><br/> Includes index and bibliographical references 
<br/><br/><label>ISBN: </label>9780285637764 
<br/><br/><label>LC Class. No.: </label>HD 53  / .B46 2006