What is the second to last digit when $$5^{7}$$ is calculated? 
Overseas Competition->Knowledge Point->Calculation Modules->Power->Computing Powers
The second to last digit is always $$2$$. For example $$5^{3}$$ is $$125$$. When multiplying this by $$5$$, we see that is it inevitable that the second to last digit remains $$2$$. Try repeated multiplication of $$5$$ on a calculator. 