# Tips and Tricks on Simplification related problems in Aptitude

1. ‘BODMAS’ Rule:This rule depicts the correct sequence in which the operations are to be executed, so as to find out the value of given expression.Here B – Bracket,
O – of,
D – Division,
M – Multiplication,
S – Subtraction

Thus, in simplifying an expression, first of all the brackets must be removed, strictly in the order (), {} and ||.

After removing the brackets, we must use the following operations strictly in the order:

(i) of (ii) Division (iii) Multiplication (iv) Addition (v) Subtraction.

2. Modulus of a Real Number:Modulus of a real number a is defined as
 |a| = a, if a > 0 –a, if a < 0

Thus, |5| = 5 and |-5| = -(-5) = 5.

3. Virnaculum (or Bar):When an expression contains Virnaculum, before applying the ‘BODMAS’ rule, we simplify the expression under the Virnaculum
A man has Rs. 480 in the denominations of one-rupee notes, five-rupee notes and ten-rupee notes. The number of notes of each denomination is equal. What is the total number of notes that he has ?
 A. 45 B. 60 C. 75 D. 90

Explanation:

Let number of notes of each denomination be x.

Then x + 5x + 10x = 480

16x = 480

x = 30.

Hence, total number of notes = 3x = 90.

2. There are two examinations rooms A and B. If 10 students are sent from A to B, then the number of students in each room is the same. If 20 candidates are sent from B to A, then the number of students in A is double the number of students in B. The number of students in room A is:
 A. 20 B. 80 C. 100 D. 200

Explanation:

Let the number of students in rooms A and B be x and y respectively.

Then, x – 10 = y + 10      x – y = 20 …. (i)

and x + 20 = 2(y – 20)      x – 2y = -60 …. (ii)

Solving (i) and (ii) we get: x = 100 , y = 80.

The required answer A = 100.