Whats the easiest way to take 20 percent off a price?

How to calculate 20 percent off

The easiest way to find 20% of any number would be multiplying the given number by 2 and shifting the decimal point 1 digits towards left.

,For example.

n20% of $45 would be 45*2=90.

Shifting the decimal 1 digit to the left gives us 9.

,Therefore, $9 is 20% of $45.

,Have a fun day!

Percent off calculator app

Lots of nice descriptions here of exact answers - great if you have a calculator handy.

Hereu2019s a rule of thumb in case (like me) you still practise the ancient methods of u2018mental mathsu2019.

,Take your speed in miles per hour.

Divide that number by two, and youu2019re in the right ballpark.

Subtract ten percent from the result, and youu2019re near enough for most everyday speeds - exact to two significant figures, and not too far away from three.

,With a bit of practice, you can do that conversion in your head before your buddy fires up the unit converter app on their phone - itu2019s a nice feeling when they find out the exact result is a couple of percent off your u2018rough guessu2019u2026

How to calculate percentage of a number

Letu2019s say you are trying to find out what percentage of u2019nu2019 is u2018xu2019.

,In that case, you can calculate the percentage by using the following formula:

How to calculate 20 percent off 100

To sign your check in record time:To calculate the amount of a 20 percent tip, calculate 10 percent (or remove the last digit) and double it.

For instance, with a $42.

50 bill, 10 percent is $4.

25 and double it to get an $8.

50 tip.

,To ace sale shopping:To find out how much youll pay for an item thats a certain percentage off, first subtract the percent off from 100.

So if its 30 percent off, use 70; 60 percent off, use 40, etc.

Divide this number and the price by 10 and then multiply the resultant two numbers.

For instance, if a $20 shirt is 60 percent off, multiply 2 by 4 for a total of $8.

A $40 shirt at 30 percent off would be 4 multiplied by 7 for a total of $28 final price.

,If you just want to calculate the amount thats coming off (not the final price), divide both numbers by 10 and then multiply the resulting numbers.

So 60 percent off $120 would be 6 x 12, for a total of $72 off.

,To see your future without a crystal ball:Use the rule of 72 to calculate how long it would take an investment to double.

The rule of 72 is that an investment that earns 10 percent interest will double in 7.

2 years.

Use this as a starting point for calculating various interest rates and lengths of time, by dividing the number 72 by your interest rate.

For instance, if you are investing at a more conservative rate of 5 percent, youd divide 72 by 5 for a total of 15 years (rounded up) for your money to double.

,To figure out how long it would take your money to triple, use 115 instead of 72.

So at an interest rate of 3 percent, it would take 38 years (115/3), for your initial amount to triple.

,To do fast house math:To calculate how much a month more youll pay in a mortgage payment for a certain increase in house price, figure roughly 6 dollars per month for every thousand dollars more in total price.

So for a house price thats $30,000 more than another, youll pay $140 more dollars a month (for a 30-year mortgage at 5 percent interest).

,To translate temperatures when you travel:For quick conversions between Fahrenheit and Celsius: Celcius x 2 + 30 = Fahrenheit and (Fahrenheit - 30) / 2 = Celsius.

,To be the fastest calculator in any room:Multiply any number by four quickly by doubling the number twice.

So 106 times four is 212 plus 212, for a total of 424.

,To multiply by five, multiply by ten and then divide in half.

So 250 multiplied by five could by calculated as 2,500 divided by 2 for a total of 1,250.

,To ease your wage wonders:Convert an hourly wage to a salary by using the formula that $1 per hour is $2,000 per year.

So if you make $10 per hour, that would translate to a $20,000 per year salary.

,Another way to compare hourly wages to a salary is to drop the three zeros of a salary and then divide by two.

So a salary of $42,000 would be roughly equivalent to $21 an hour.

Conversely, multiply an hourly rate by two and add three zeros to the total to figure out a salary from an hourly wage.

,To analyze the impact of that coffee habit:To estimate the annual cost of a daily habit, multiply to find the weekly total amount you spend (so, times 5 if its a weekday habit, or times 7 if its every day a week.

Then add two zeros to that number, and divide by two.

So a $12 a day lunch five days a week will roughly set you back a whopping $3,000.

(Just dont do it.

),To know how hard you have to study:To quickly and roughly figure out what number you need to make a certain average, add together how far off you were from your target in each instance.

Then add that resulting number to your target average for your final chance.

For instance, if your scores are 90, 90, 85, and 95 and youre hoping for a total average of 89, youd add 1+1-4+6 for a total of 4.

So youd need to make 89+4, or 93, on your final test.