How to increase aptitude level? can you suggest some books ?

Combined aptitude and knowledge tests  Tests that assess learned skills or knowledge are frequently called achievement tests. However, certain tests can assess both types of constructs. An example that leans both ways is the Armed Services Vocational Aptitude Battery (ASVAB), which is given to recruits entering the armed forces of the United States. Another is the SAT, which is designed as a test of aptitude for college in the United States, but has achievement elements. For example, it tests mathematical reasoning, which depends both on innate mathematical ability and education received in mathematics.  Aptitude tests can typically be grouped according to the type of cognitive ability they measure:    

1. Fluid intelligence: the ability to think and reason abstractly, effectively solve problems and think strategically. It’s more commonly known as ‘street smarts’ or the ability to ‘quickly think on your feet’. Examples of what employers can learn from your fluid intelligence about your suitability for the role for which you are applying  

  2. Crystallised intelligence: the ability to learn from past experiences and relevant learning, and to apply this learning to work-related situation. Work situations that require crystallised intelligence include producing and analysing written reports, comprehending work instructions, using numbers as a tool to make effective decisions, etc

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