Tom boughts $$1000$$ bottles for his science laboratory. Among them, one bottle had poison in it. When mixed with chemical $$X$$, this poisonous water will change its colour while the bottles without poison will not have its colour changed. Every mixture takes $$6$$ hours for the result to be observed as every mixture requires one test tube. What is the least number of test tubes that is required so as to find out which bottle contains poison in them? 
Overseas Competition->Knowledge Point->Word Problem Modules->Equation Word Problems->Multivariate Linear Equation Word Problems->Solving Problems by Solving System of 
Binary Linear Equations with Integer Coefficients 