Cotsworth, M. B.  <br/><br/>
Cotsworth's direct calculator   containing over 1,000,000 distinct calculations for expediting and ensuring accuracy in multiplication, division, average, percentage, interest, exchange and general calculation by all combinations of numbers from 1 to 1000 ... 
M. B. Cotsworth 
 - London  M. B. Cotsworth  1896 
 - 400p. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Calculator
<br/><br/><label>Universal Decimal Class. No.: </label>519.672  / COT