Problem solving consists of using generic or ad hoc methods, in an orderly manner, for finding solutions to problems. Some of the problem-solving techniques developed and used in artificial intelligence , computer science , engineering , mathematics , or medicine are related to mental problem-solving techniques studied in psychology.
Considered the most complex of all intellectual functions, problem solving has been defined as a higher-order cognitive process that requires the modulation and control of more routine or fundamental skills.  Problem solving has two major domains: mathematical problem solving and personal problem solving where, in the second, some difficulty or barrier is encountered. 
Guidelines to Problem Solving and Decision Making
Rational Versus Organic Approach to Problem Solving and Decision Making
General Guidelines to Problem Solving and Decision Making
Various Methods and Tools for Problem Solving and Decision Making
General Resources for Problem Solving and Decision Making
Regardless of what they do for a living or where they live, most people spend most of their waking hours, at work or at home, solving problems. Most problems we face are small, some are large and complex, but they all need to be solved in a satisfactory way. Before we look at the area of problem analysis and solution, though, let''''''''s take a few moments to think about just what we mean by a problem.
1. A problem is an opportunity for improvement. A problem can be a real break, the stroke of luck, opportunity knocking, a chance to get out of the rut of the everyday and make yourself or some situation better. Note that problems need not arrive as a result of external factors or bad events. Any new awareness you have that allows you to see possibilities for improvement brings a "problem" for you to solve. This is why the most creative people are "problem seekers" rather than "problem avoiders."
As with creative thinking, flexibility is a crucially important feature in problem solving. Many of these techniques you will begin to use regularly for each major problem you address. Others you will use selectively.
1. They set limits to the problem and thus provide a framework within which to work. These limits might include constraints of possibility, economics, or some other desired narrowing.
The McKinsey Problem Solving Test (also known as the McKinsey PST) is a math computation, data interpretation and logical thinking test used by McKinsey to determine which candidates are granted a first round case interview. In general, candidates whose resumes McKinsey deems acceptable are invited to take the test. Based on feedback from hundreds of test takers, you must pass the test in order to get the interview. There are few to no exceptions to this rule.
The reason McKinsey uses the test is because there are a certain set of numerical computation and logical thinking skills required to be successful in consulting. While standardized math tests like the quantitative sections of the SAT, GRE, or GMAT do test math computational skills, it is possible to get perfect scores on these math tests but fail on the job in consulting.