Can You Pass This Mental Calculation Math Quiz?


By: Jonnathan Chadwick

7 Min Quiz

Image: franckreporter / E+ / Getty Images

About This Quiz

Even if math isn't your strong suit, mental calculation is a necessary part of life. Every time you buy something, travel somewhere, eat something, see something, drink something or do something, you have to perform some mental calculations to help make your decision. Being able to mentally calculate simple math is extremely helpful when deciding between prices, discounts and deals.

Let's say one jar of peanut butter is $6 and another jar is $2, but the $6 jar contains 120 ounces and the $2 jar contains 50 ounces. Which is the better deal? In this scenario, the $6 jar costs $0.05 per ounce and the $2 jar costs $0.04 per ounce, but you just need to multiply $2 times three, to see that you can get 150 ounces of peanut butter with three $2 jars, or 120 ounces with one $6 jar. Some simple math can help you save money in everyday situations.

Even more important than money is time, and without mental calculation, time is nothing but a number. If we know that it's 4:33 p.m., that means nothing unless we know what time it gets dark, what time the day ends and how long we have before midnight. Once we calculate how much time is left in the workday, 4:33 p.m. actually means something.

You can't live life without performing mental calculations every day. Do you think you can pass this mental calculation quiz?

What is the next number in this sequence: 2, 4, 8, 16, 32 ...

Each number in this sequence is simply doubled, so the next number is double of 32, which is 64. This number sequence goes on forever and each number will always be even since the sum of two even numbers is always even.


A direct flight from NYC to LA is 2,500 miles. If a plane travels 500 miles per hour, how long does the flight take?

A plane that flies 500 miles per hour will need to travel for five hours to cover 2,500 miles. Most direct LA to NYC flights will take a bit more than five hours once you account for boarding and landing times.


If an hour-long TV show has 16 minutes of commercials, what is the actual duration of the show?

If you're watching a 60-minute program on cable television, it will likely contain about 16 minutes of commercials, meaning the actual program is only 44 minutes long. If you're watching premium TV or a streaming service, you might bypass commercials altogether.


There are only 22 chocolate bars in the 36-pack you bought yesterday. How many chocolate bars are missing?

This is simple subtraction. To answer the question you just have to solve 36 - 22, which equals 14. Regardless of size, 14 candy bars is a lot of candy bars and isn't a recommended amount of candy to eat in one sitting.


If your cellphone battery burns 7% of power per hour, how long will a 35% battery level last?

If your cellphone battery burns 7% per hour, and you have 35% battery life left, you just need to divide 35 by 7 to figure out how long until your battery dies. In this situation, 35/7 = 5, so a 35% battery life will last five hours.


An airplane has five columns of 30 seats in one cabin and 10 rows of three seats in another cabin. How many seats are in total?

There are 30 seats in each column and there are five columns, so that means you have (30 x 5) 150 seats in one cabin. There are three seats in each row in the other cabin and 10 rows total, so that means there is (10 x 3) 30 seats in the other cabin. 150 + 30 = 180 total seats.


If you make $10 an hour and you work three days a week for four hours each day, how much money will you make after 10 weeks?

If you work three days a week at four hours per day, you log 12 hours of work per week. If you make $10 per hour, you can multiply 10 by 12 to equal 120. If you make $120 a week, you will make $1,200 in 10 weeks ($120 x 10).


If you make $60,000 per year and 25% goes to taxes, how much do you pay in taxes each year?

The easiest way to find any percent of any number is to first find 10% of the number. To find 25% of 60,000, just find 10%, which is 6,000. To find 20%, just double 10% (6,000 x 2 = 12,000). To find 5%, just split 10% in half (6,000/2 = 3,000). Then add the results together (12,000 + 3,000 = 15,000).


Monday started with 275 books in the library. A total of 125 were checked out and 75 were returned. How many books were in the library at the end of Monday?

This problem is simple addition and subtraction but the values have to be calculated in the correct order. If you start with 275 and subtract 125, you're left with 150. And if 75 books are added to 150, you're left with 225.


How do you write 4:20 p.m. in military time?

In order to convert the time to military time, you just have to add it to 12 (noon). So 4:20 pm is 12 + 4:20 and equals 16:20. What Americans refer to as military time is known around the world as the 24-hour clock and it makes a.m. and p.m. distinctions unnecessary.


Andrea shot four three-pointers and 12 two-pointers during the game. What percentage of her shots were three-pointers?

Andrea shot 16 shots in total during the basketball game and four of them were three-pointers. Half of 16 is eight, and half of eight is four, which is 25% of 16. The easiest way to mentally calculate percentages is by finding 10% or 50% of the number and using it as a starting point.


If a box is filled with 10 rows of 10 candy bars that are stacked 10 bars high, how many candy bars are in the box?

The formula for volume is length x width x height, so for this equation all you have to do is solve 10 x 10 x 10, which equals 1,000. If a box can hold 10 rows of 10 candy bars stacked 10 bars high, it can hold 1,000 candy bars.


If you're 6'2'' and your arm extends two feet above your head, how high do you have to jump to dunk a 10-foot basketball hoop?

If you stand 6'2'' and your arm extends two feet above your head, that means you can reach something that is eight feet and two inches high. A standard basketball hoop is 10 feet, so if you want to reach the rim, you'd have to jump one foot and 10 inches, or 22 inches.


One out of every four people at the Halloween party was dressed as Dracula. There were 200 people at the party. How many people were dressed as Dracula?

All you have to do to figure this problem out is divide 200 by four to equal 50. If there are 50 people dressed as Dracula at the 200-person party, then one out of every four people is dressed as Dracula.


If you sleep eight hours, work eight hours and eat for three hours every day, how much free time do you have left?

Eight plus eight is 16 and plus three is 19. There are 24 hours in a day, so 24 - 19 = 5. If you follow this routine, you only have five hours of free time per day. If you sleep or work more than eight hours per day, your free time shrinks even more.


What is the next number in this sequence: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55...

This is the classic Fibonacci sequence, which is probably the most important number sequence in the history of number sequences, and each number is the sum of the previous two numbers. The next number is 55 + 34 = 89.


How fast do you need to drive if you want to travel 50 miles in 30 minutes?

If you need to travel 50 miles in 30 minutes, you're likely not going to make it because you would have to drive 100 mph the entire way. At 100 mph you will travel 100 miles in an hour, and 50 miles in a half hour.


How many different letters are in the word "Mississippi"?

Mississippi is one of the longest state names at 11 letters long, but it only has four different letters: m, i, s and p. The capital of Mississippi is Jackson and is named for the seventh President of the United States, Andrew Jackson.


America declared its independence in 1776. When is America's 250th birthday?

In 1876, the United States held nationwide centennial celebrations. In 1976, the nation held bicentennial celebrations. In 2026, the country will hold semiquincentennial celebrations to observe the nation's 250th anniversary.


If you walk at a pace of three miles per hour, how long will it take you to walk 10 miles?

If you walk three miles per hour, it will take you three hours to walk nine miles. And since you are walking at a pace of one mile every 20 minutes, you will walk 10 miles in three hours and 20 minutes.


You brought $7.75 to the corner store and bought a soda for $1.25, a bag of chips for $0.50 and three pieces of candy at $0.10 each. How much money do you have left?

Nobody likes adding and subtracting decimals but it's a necessary function of life. You started with $7.75 then subtracted $1.25 to equal $6.50. Then a bag of chips costs $0.50 and drops you to $6.00, and three pieces of 10-cent candy costs $0.30 in total, leaving you with $5.70.


James made $250 after selling cookies for $0.25 each. How many cookies did he sell?

In this scenario, James has to sell four cookies to make $1. He then has to do that 250 times in order to make $250. So if four cookies make a dollar, you can use 250 x 4 = 1,000. James sold 1,000 cookies at $0.25 a piece to make $250.


How many feet are in a meter?

A meter is 3.28 feet and is a common unit of measure around the world. It is more accurately equivalent to 100 centimeters, which is 39.37 inches. In order to be crowned the fastest person in the world, you have to win Olympic gold in the 100-meter dash.


Every single baseball game last season, Mike got exactly one more hit than Jake. Which of the following equations can you use to find Mike's hits per game?

If Mike got exactly one more hit than Jake in every baseball game, you can accurately calculate the amount of hits he got per game by knowing how many hits Jake got and using the formula: Jake's hits + 1 = Mike's hits.


Three pizzas were ordered for the pizza party. Each pizza had eight slices. Seven people ate two slices each, and one person ate five slices. How many slices were left over?

If there are three pizzas with eight slices each, there are 24 slices of pizza in total. Seven people each ate two slices, which equals 14 slices in total, and one kid ate five slices to bring the total to 19 slices. That leaves five uneaten slices of pizza.


If you begin taking a test at 2:32 p.m. and finish at 3:17 p.m., how long did the test take?

It's not fun to add and subtract time values and everything is extra complicated because there are only 60 minutes in an hour instead of 100, but it's a skill everyone needs to know. If you starts at 2:32 p.m. it will take 28 minutes to get to 3:00 p.m., and then 28 + 17 = 45.


What is the next number in this sequence: 1, 3, 7, 15, 31...

The numbers in this sequence follow the formula: (n x 2) + 1. So (1 x 2) + 1 = 3, (3 x 2) + 1 = 7, (7 x 2) + 1 = 15 and (15 x 2) + 1 = 31. The next number in the sequence is (31 x 2) + 1 = 63. There is no easy trick to figuring out all number sequences since each one is so different.


What is the next number in this sequence: 2, 6, 14, 30, 62 ...

This sequence of numbers follows the following formula: (n + 1) x 2. So (2 + 1) x 2 = 6, (6 + 1) x 2 = 14 and (14 + 1) x 2 = 30. The next number in this sequence is (62 + 1) x 2 = 126. It would then go to 254 and 510.


If you deposit $10,000 into a bank account that gains 2% interest per year. How much money in interest will you accrue after 5 years?

A normal savings account isn't the best way to multiply your money. If you put $10,000 in an account that gains 2% interest, you will gain $200 in interest each year. You will net $1,000 in interest over the course of five years.


A jar of almond butter costs $6. If you buy 2 and get 1 free, how much does each jar cost?

Two jars of almond butter cost $12, and if you get a third one free, it equals three jars of almond butter for $12. Twelve divided by three equals four. With this discount, each jar of almond butter will technically cost $4.


If you post 10 Instagram pictures and five of them receive 100 likes and five of them receive 50 likes, what is the average amount of likes each post receives?

To find the average you have to add up all the likes (100 x 5 = 500) + (50 x 5 = 250) = 750 likes, and then divide them by the number of Instagram posts, which is 10 (750/10 = 75). Each Instagram post receives 75 likes on average.


If you have 180 tickets and a drink costs seven tickets, how many drinks can you get?

The number 180 isn't evenly divisible by seven, but you can use 7 x 20 to get to 140. Then you know 7 x 5 = 35, and 35 + 140 = 175. Twenty-five drinks will cost you 175 tickets, and you will have five tickets left over, which isn't enough to get a 26th drink.


The formula to roughly convert Fahrenheit to Celsius is (F - 30)/2. What does 82 degrees Fahrenheit convert to in Celsius?

If you want to convert 82 degrees Fahrenheit to Celsius you first have to subtract 30 (82 - 30 = 52) and then divide by two (52/2 = 26). The exact conversion is 27.7 degrees, and if you want the exact conversion, use 32 and 1.8 in place of 30 and 2.


How many miles are in a 5K race?

One mile equates to about 1.6 kilometers and a 5K race equates to 3.1 miles. A kilometer is 1,000 meters, which itself is 1,000 centimeters. The meter runs the metric system and it might be the most popular unit of measure in the world.


What does 25,000 x 400,000 equal?

Whenever you're multiplying numbers that end in zeros, all you have to do is multiply the initial numbers and then place all the zeroes onto the end of the result. For this example just multiply 25 x 4 (100) and then add eight zeroes (10,000,000,000). The answer is 10 billion.


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