A computer can do $$7\times {{10}^{9}}$$ operations per second. Then, it can do~\uline{~~~~~~~~~~}~operations in $$5\times {{10}^{2}}$$ seconds. 
Overseas Competition->Knowledge Point->Number Theory Modules->Perfect Square Numbers->The Relationship between Exponents and the Number of Factors
$$7\times {{10}^{9}}\times 5\times {{10}^{2}}=3.5\times {{10}^{12}}$$ 