Ever wondered about those irritating ‘*Solve it if you are a genius*‘ or ‘*90% will get it wrong*‘ puzzles that flood your Facebook and LinkedIn pages?

Often on the same image, they also have a confused looking Einstein staring back at you wondering why he’s being dragged into this frivolous race for social media domination.

Most of these ‘genius’ level puzzles are basic maths problems that you feel compelled to solve and share, just because 5 of your friends did the same.

Apart from the little kick you get from cracking them, there’s more to it.

Some of the concepts are building blocks based on which more complex problems are designed in aptitude tests like the GMAT, GRE, CAT etc. The most basic rule among them is the order of operations.

The basic operations in mathematics, as everyone knows, are addition, subtraction, multiplication and division.

In algebra, these operations are used with numbers or letters or a combination of both.

A number or variable or number multiplied by a variable is called a ‘term’.

A combination of such terms with operators results in an ‘expression’.

For example: In 2a+b, 2a and b are called terms and 2a+b is called an expression.

Some typical examples of algebraic expressions look like this

1) 2+3(8-4)-6/3

2) 10+7(3-1)*8/2^{2}-1

3) x+2(4x-5)+3(2(x+6))

**Definition: **The order of operations is defined as the sequence in which operations are performed on a given mathematical expression.

Ever wondered why we need to follow a sequence while calculating?

Consider the expression: 2+3(8-4)-6/3

Which one of these is the correct way of solving it?

**Method 1:**

__2+3__(8-4)-6/3 → 5(__8-4__)-6/3 → __5(4)__-6/3 → __20-6__/3 → 14/3 → 4.6666

**Method 2:**

2+3(__8-4__)-6/3 → 2+__3(4)__-6/3 → __2+12__-6/3 → __14-6__/3 → 8/3 → 2.6666

**Method 3:**

2+3(__8-4__)-6/3 → 2+__3(4)__–__6/3__ → 2+12-2 → 12

Every expression can be calculated in more than one way and can result in more than one answer. Of course, not every answer is correct. This is where and why we need to apply the ‘order of operations’.

The Order of operations for any given expression is governed by the following rule:

OR

**B**rackets → **O**rders → **D**ivision → **M**ultiplication → **A**ddition → **S**ubtraction

According to the US learning system, it is ‘PEDMAS’ (Some remember it as ‘PEMDAS’ too). According to the UK learning system, it is ‘BODMAS’.

**Parentheses or Brackets**are always the first to be resolved in a given expression and are evaluated starting from the innermost ones.**Exponents or Orders**are given the next priority.**Division and Multiplication**are the next and are treated to be on the same level of precedence.**Addition and Subtraction**are the last and are treated to be on the same level of precedence.

When operators on the same level of precedence are found, as a thumb rule, we work from left to right.

Nothing like a few ridiculously simple examples to get some clarity.

Consider an expression like this:

4(2+(7(5-3)))

Here the innermost parentheses has (5-3). That is the first to be evaluated.

4(2+(7(2)))

Then comes the 7(2) which is in a parentheses

4(2+14)

Next in the parentheses is 2+14

4(16)

Result is 64

Consider an expression like this

5(2^{2}+3)+(2^{3})^{2}

The expression inside the parentheses is 2^{2}+3 (starting from left to right). Following PEDMAS, we need to evaluate the exponent first before we do the addition, which results in (4+3).

It is important to note here that 2^{2}+3 is different from (2+3)^{2}.

Now, our expression looks like this:

5(4+3)+(2^{3})^{2}

Next, we see (4+3) inside a parentheses.

5(7)+(2^{3})^{2}

There is an exponent to be evaluated before further operation is performed.

5(7)+8^{2}

5(7)+64

Next comes the multiplication.

35+64

And finally the addition.

Result is 99

Consider the expression

6*2+5*1+4/2+1

Applying our thumb rule of working from left to right,

__6*2__+__5*1__+__4/2__-1

results in

12+5+2-1

Now, all that’s left is additions/subtractions

18 is our answer.

Note here that performing the addition/subtraction before any multiplication/division is performed would result in wrong answer.

Consider the expression:

1+(2(4-3+1)+7)-2

Evaluating the parentheses first,

1+(2(2)+7)-2

Next there is a multiplication

1+(4+7)-2

Evaluating the expression inside the parentheses.

1+11-2

Finally the addition/subtraction.

Our answer is 10.

Sometimes, operations performed in any order would yield the same result.

For instance, in the above example, the calculation of 1+(4+7)-2 would yield the same result when performed in any order.

However, when performing the operation from right to left, it is important to note the ‘-‘ sign before 2, forgetting which, results in erroneous answer.

**Example 1:** 2+3(8-4)-6/3

Applying PEDMAS, going from left to right, first is the parentheses

2+3(4)-6/3

There are no exponents here. Performing the multiplication/division

2+12-2

And finally the addition

12 is the result.

**Example 2:** 10+7(3-1)*8/2^{2}-1

Going from left to right, parentheses is the first

10+7(2)*8/2^{2}-1

Next, there is an exponent to be evaluated

10+14*8/4-1

Next comes the multiplication/division

10+28-1

Last comes the addition/subtraction

37 is the result.

**Example 3:** x+2(4x-5)+3(2(x+6))

Working on the innermost parentheses first and then the outer ones,

x+2(4x-5)+3(2x+12)

There are no exponents and no divisions.

Performing the multiplication

x+8x-10+6x+36

And finally, addition/subtraction

15x+26 is the result.

Solve these to see if you’ve got the concepts and rules right.

Problem 1

**Simplify this expression:** (20-18)^{3}/8*3-1

**Choose your answer:**

A. 1/2

B. 2

C. 8

D. 8/23

Answer 1

B.

Problem 2

**Simplify this expression:** (2.3+1.9+3+3.7+4.1)2-1*4^{2}

**Choose your answer:**

A. 464

B. 240

C. 14

D. None

Answer 2

C.

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## 3 Comments

Hi I am a operations services professional currently working for Oracle at Bangalore,I have close to 12 years of work experience mostly from the BPO sector. B.Com from Osamanai University.I was an above average student back then. I have a major mind block for maths hence I dread taking the GMAT or CAT however I want to invest one year in a full time MBA which will give me substantial hike in my career and pay check, What would you suggest ?

Hi Sameer,

I am 32, working with media MNC with an experience of over 7 years. I am an Engineering graduate with full time post graduation in Marketing from a tier-2 institute. I am planning for one year MBA with a goal of career advancement and change of location. I would be writing GMAT soon for the same.

Could you pls suggest the pros and cons in this endeavor?

Thanks

Anurag

HI,

I am BSc Graduate (Maths,Electronics,Cs) , i am working for reputed company and i have 2 yrs experience in this company. Since i am UG , i want to pursue my PG. But here in completitive world i am confused what i need to do.

CAT+MBA , MSC(elec/IT) +Ph.d or any write exams like IBPS,RBI etc.

Also does MBA or MSc distance education is valuable?

CAT+MBA after a 2yrs journey here , what will be my postion?

could you suggest me how i can go thorugh it and what will be better for me?