# Percentage Maths Trick, Question with solution

**Percentage Maths Trick, Question with solution**

**PERCENT**

The word percent means “divided by hundred”. The word percent come from “Per Centum” The word centum means hundred.

Percent means ” out of 100″ . we use the percent symbol is %.

A percent can always be written as a decimal, and a decimal can be written as a percent, by moving the decimal point two places to the right like this;

0.75= 75%

Here are three ways to write the same thing:

0.75=75%=75/100

We can find any percent of a given number by changing the percent to a decimal and multiplying.

* Lets’s find 20 percent of 400*

First change 20% to a decimal by moving the decimal point 2 places to the left.

20%= 0.20

Then multiply,

0.20*400=80

20% of 400 is 80

** MENTAL MATH**

There’s an easy way to find 10% of a number without multiplying. just move the decimal point in the number left by one place.

* Let’s try bit with these number:*

456,76,56457

10% of 456= 45.6

10% of 76= 7.6

10 % of 56457= 5645.7

**APPLY LITTLE PRESENCE OF MIND AND CALCULATE PERCENTAGE AS ****FAST AS YOU CAN: **

**Example:**

Que: 24 is 6% of what number?

Ans: 24=6%*n

n= 24/6%

n= 400

**PERCENT INCREASE AND DECREASE**

We need to find the percent of increase or decrease in a given quantity. to find this calculate the increase and divided it by the original amount.

*This can be represented as*

Percent increase of a quantity= (Actual increase/ original Amount)* 100%

Percent decrease of a quantity=( Actual decrease/ original Amount)*100%

Generalising this , we can write as

Percent of change= (Amount of change/Original amount)*100%

**SOME COMMON PERCENTS AND THEIR FRACTIONAL EQUIVALENTS: **

**EXAMPLE:**

**Question:** Mohit bought a new car in 1995 for 10,000rs in 2000 the car was priced at 18,500. Calculate the percentage increase in the car over the five years.

10,000+(a% of 10,000) = 18,500

Hence a% of 10000= 8,500

Using the formula:

10,000* a/100= 8500

100a=8500

a=8500/100=85%

**CONVERSION OF DECIMAL, FRACTION & PERCENT**

Decimal to Fraction

ab.cde= (10a)+b+(c/10)+(d/100)+(e/1000)

=abcde/1000

Fraction to decimal

Divided the numerator by the denominator.

3/7= 0.4285

Decimal to percent

Move the decimal points two places to the right

0.36= 36%

Fraction to percent

Divided the numerator by the denominator. then move the decimal point places to the right.

3/7= 42.85%

**CONVERSION OF DECIMAL INTO FRACTIONS**

**STEP 1.**

Count the number of decimal places.

Ex. 0.445 (three decimal places)

**STEP 2.**

Find the denominator of the fraction using the following table.

**STEP 3.**

Write the decimal digits without the decimal point as the numerator.

445/1000

**STEP 5.**

Reduce the fraction to its lowest term.

445/1000=89/200

**EXAMPLE:**

Que: If result of increasing by 300% of a is b, then a is what percent of b?

Ans:

Here is given that a is increased by 300% of a

Now, 300% of a= 3a

If 3a is added to a, then result of increase in a

=a+3a

=4a

It is given that the result of increases is equal to b.

4a=b

a=b/4

Now 1/4=25%

a=25% of b.

**Check also:** Basics of Simple Interest & Compound Interest (SI and CI Basic concept)