Mathematical Operations

A mathematical operation means calculation by mathematical methods. Here, the four fundamental operations — addition, subtraction, multiplication and division and also statements such as ‘less than’, ‘greater than’, ‘equal to’, not equal to’, etc. are represented by symbols, different from the usual ones.  The questions involving these operations are set using artificial symbols.  The candidate has to substitute the real signs and solve the questions accordingly, to get the answer.

Basic mathematical operators are:

Addition         ‘+’
Subtraction    ‘-‘
Multiplication   ‘×’

Division         ‘÷’

TYPE 1: Problem-Solving By Substitution

In this type, substitutes for various mathematical symbols are provided, followed by a question involving calculation of an expression or choosing the correct/incorrect equation.  The candidate is required to put in the real signs in the given equation and then solve the questions as required.

While solving a mathematical expression, proceed according to the rule of BODMAS i.e,

B        Brackets

 

O        Orders (i.e. Powers and Square Roots, etc.)

 

D        Division

 

M        Multiplication

 

A        Addition

 

S        Subtraction

 

Example:      Solve: (36-12) ¸ 4 + 6 ¸ 2×3

Solution:      = 24 ¸ 4 + 6 ¸ 2×3            (Solving Bracket)

                   = 6 + 3 × 3                      (Solving Division)

                   = 6 + 9                            (Solving Multiplication)

                   = 15                                (Solving Addition)

TYPE 2: Interchange of Signs and Numbers

Example:      Which one of the four interchanges in signs and numbers would make the given equation correct?

3 + 5 – 2 = 4

 

  1. + and –, 2 and 3
  2. + and –, 2 and 5
  3. + and –, 3 and 5
  4. None of these

 Solution:      By making the interchanges given in (a), we get the equation as 2 – 5 + 3 = 4 or 0 = 4, which is false.

                   By making the interchanges given in (b), we get the equation as 3 – 2 + 5 = 4 or 6 = 4, which is false.

                   By making the interchanges given in (c), we get the equation as 5 – 3 + 2 = 4 or 4 = 4, which is true.

                   So, the answer is (c).