A Lot of students find Mathematics as a very difficult subjects as it involves mental exercise. Calculation speed plays very important role during competitive exams as lots of exams are based on speed test. Most of students are accustomed of using calculator during their graduation so they find difficult to calculate fast during competitive exams. By learning some shortcut tricks they can also get good marks in this section. Improving calculation speed is time taking process. It will improve with time and practice.
First one would have to learn some essentials for calculation by heart
Table- up to 30×30
Reciprocal- Up to 30
Squares- up to 30
Cubes- up to 30
Square root- up to 15
Cube roots up to 15
Does it seem huge task? Well I’d say no. By using smart approach the works involved is not as high as it seems.
Consider the case of table if one knows 6×8 is 48 then by using some common sense one can get that 12×8 will be twice i.e. 96. Similarly tables of 18 is known if tables of 9 is known. You can also get the tables of many numbers by using this logic. So carrying this logic forward you will need to remember the table of 13, 17, 19, 23 and 29.
Reciprocal percentage is going to help you lot in division part of quant section. If reciprocal of 2 is 50%, then 4 will be half of 50% i.e. 25%. Similarly 8 be half of 25% i.e. 12.5%. Reciprocal of 3 IS 33.33% then 6 will be 16.66%.
Reciprocal of 9 is 11.11 and reciprocal of 11 is 9.0909. Reciprocal of 9 is composed of 11s and reciprocal of 11 is composed of 09s. So by using smart approach you can also get reciprocal of many numbers.
If one knows reciprocal of 8 is 12.5% then 2/8 will be just double i.e 25% , 3/8 is 37.5% and so on. so lets say if one has to find 37.5% of 128. then it will be nothing but