Find the number of digit of $$A$$ if $$A=\underbrace{4\times 4\times 4\times \cdots \times 4}_{{{2018}^{\prime }}s}\times \underbrace{25\times 25\times 25\times \cdots \times 25}_{{{2018}^{\prime }}s}$$. 
Overseas Competition->Knowledge Point->Number Theory Modules->Perfect Square Numbers->The Relationship between Exponents and the Number of Factors