http://faq.casio.com/faq/calc/faq_type_b.php?PRODUCT=General%20Calculator&CATEGORY=Grand%20Total
Q1. What is the purpose of the GT Key?
A1. Whenever the “=” Key has been pressed, the result will be stored into the Grand Total Memory!
The “GT” Key is to recall the Grand Total Memory!
It’s function is similar to the “MR” Key, both of them are used for recalling the Memory Content!
Please note that the GT Memory will be cleared by pressing the “AC” Key in most of the CASIO Models! For other Models, it can only be cleared by pressing the “GT” Key twice!