If a baseball and bat cost $110, and the bat costs $100 more than the ball, how much does the ball cost?

This problem is so old that I remember doing it once upon a time where the bat and ball cost $1.10. The prices really have soared. Occupy Sports Authority.

As crudely illustrated above, there are seven sisters standing around the kitchen table. Each one has seven backpacks. In each backpack, there are seven large cats. For every large cat, there are seven small cats. How many legs are there in the room?

Get this right and you’ll get a scholarship to the Seven Sisters college of your choice. And a hot plate!

At first glance, it looks easy. But it’s stumped many over the years, starting in Japan.

The problem went viral in Japan after a recent study found only 60 percent of people between the ages of 21 and 29 could get the correct answer–down from 90 percent in the 1980s.

Despite appearing simple, Presh Talwalker of Mind Your Decisions noted what had fooled most people.

“You should write an expression that groups one third as one group,” he says in the video.

“Three divided by one third is equal to nine, and now we have nine minus nine, plus one,” he added

The solution harkens back to an acronym some likely learned in school: BODMAS, or brackets, open; divide; multiply; add; and subtract, in that order.

It’s also known as PEMDAS, or parentheses first, exponents (ie powers and square roots) next, multiplication and division (left-to-right), and addition and subtraction (left-to-right).

More Math Problems

Another viral math problem is:

There were some people on a train.
19 people get off the train at the first stop.
17 people get on the train.
Now there are 63 people on the train.
How many people were there on the train to begin with?

Here’s the answer to the problem:

There are 63 people on the train, meaning that one would subtract the 17 people who boarded the train.

Then you would have to account for the 19 people who got off, and one then has to add 19 and 46.

That gives 65, the answer, meaning there were 65 people on the train to start.

Or one could subtract 19 people by 17 people, which equals 2. Then add the other 63 to 2, which equals 65.

Louise Bloxham posted the problem to Twitter, confusing a number of people by stating the answer is 46. But that only solves the first portion of the problem.

As the Metro noted, “people said that the 19 was a red herring, which doesn’t make sense, or that the train was empty to begin with, which doesn’t make sense. It even says there are ‘some people’ on the train.”

Americans Bad at Math?

It’s been noted that Americans aren’t great at math compared to other developed countries.

“Americans continually score either in the mid- or bottom-tier when it comes to math and science compared to their international peers,” says BigThink. “Students have a fundamental misunderstanding of what math is and what it can do. By viewing it as a language, students and teachers can begin to conceptualize it in easier and more practical ways.”

It says that Americans worry too much about “rote memorization,” and students have a difficult time learning the concepts in sequential order.

“Unlike the more difficult and comprehensive math tests given to test students’ comprehension, this test was for basic numeracy skills. The United States fell behind in 22nd place,” it says.

Suppose your water heater broke so you couldn’t take a hot shower. You go to a person and ask them to check out your water heater. That person comes to your house and uses a bunch of spare parts and then fixes it so you pay him or her for the repairs. Is this person more likely:

An accountant?

OR

An accountant and a plumber.

Did you answer a plumber? That’s understandable, but you’re wrong.

The Answer: The person is most likely an accountant.

The Explanation: When you read this word problem, you intuitively jumped to the conclusion that the person was most likely a plumber because, well, plumbers fix water heaters. BUT, the question asks what is more likely, which means it’s a probability question.

Strictly speaking, it’s more likely s/he’s an accountant than a plumber. The key to remember here is that the question asks if the person who fixes the heater is most likely an accountant or an accountant and a plumber (AKA, a plumber-accountant).

So, the probabilities are that

[A] a plumber-accountant fixed your heater (probably very small, right? Not many people are both licensed plumbers and accountants),

[B] an accountant fixed your heater (there are probs waaaaaay more accountants than plumber-accountants)

And then, in this situation, any plumber is definitely also an accountant, so you actually add those probabilities together.

A ≤ A + B

or

Plumber-Accountants ≤ Plumber-Accountant + Accountants

So, it was most likely an accountant!

Let’s start out easy. Add the following numbers from top to bottom as quickly as you can in your head.

Did you get 5000? Well, that would be… wrong.

The Answer: 4100

The Explanation: This is just a simple case of your brain getting ahead of itself. You were probs totally on a roll until you got to to the last addition.

1000 + 20 = 1020 (Right.)

1020 + 30 = 1050 (Totes.)

1050 + 1000 = 2050 (Yup.)

2050 + 1030 = 3080 (Mhmmm.)

3080 + 1000 = 4080 (Yassss, almost done!)

4080 + 20 = 4100

Errrr, what?! You def didn’t get that before.

It seems totally obvious now that it’s all done out slowly in front of you, but what made you slip up on that last addition the first time around is that when you were adding everything up quickly in your head, you never had to carry any ones until the very end, and when you finally do have to carry a one, you accidentally added it to the thousands spot rather than the hundreds because you were going so quickly. Or maybe you didn’t spot the 30 in the 1030 of the third to last line.

Or, maybe you’re just a genius and you were right the first time in which case, good on you!

Well, everyone knows that putting … at the end of three nines in a row means that 9 goes on infinitely, so you answered false. 0.999… could never equal 1, right?

Answer: Nope. Wrong. It is, in fact, equal to one. Here’s a proof to prove it:

The Explanation: The reason this is so hard to grasp is because the concept of infinity is just kind complicated to grasp in the first place. Most people just imagine that there’s a last 9 somewhere down the line. But the thing is, the 9s are never-ending.

It’s also important to remember that just because two numbers look different doesn’t mean they’re not the same value. 0.5 is definitely the same as 1/2. And 2 + 2 is the same as 4. And 0.999… is absolutely equal to 1. It’s just two different ways of expressing the same value.

Here’s another, even simpler proof that might help you understand. We all agree that 1/3 = 0.333… repeating, right? Well, check this out:

See! It’s actually pretty simple! If you’re still having a hard time grasping it, let expert YouTube explainer, ViHart, explain it to you in complete detail (and with fun doodles).

Did you multiply the 1 x 0 first and then add the rest of the ones together and get 12? Wrong!

The Answer: The answer is 2. Yes, 2!

The Explanation: Since there are no operator symbols (+, -, x, /) at the end of each line, there’s no mathematic reason to believe that each line is part of the same equation. And since an equation is a statement that the values of two mathematical expressions are equal, since there are no equal signs at the ends of the first two lines, they’re not equations at all. They’re just expressions. That means the only equation in the picture above is the last line, and:

1 + 1 x 0 + 1 = 2

Some argue that you should string the lines together, making the two ones at the end of each line 11s, in which case the answer would be 30 because:

1 + 1 + 1 + 1 + 11 + 1 + 1 + 1 + 11 + 1 x 0 + 1 = 30

But this isn’t really mathematically sound because math isn’t like English. You don’t just “keep reading” onto the next line (that would cause a lot of confusion and ambiguity in math problems). If you have a long equation that must be split on multiple lines, the line break must come immediately before or after an operator symbol. So if 30 was meant to be the answer, the problem should have been written:

1 + 1 + 1 + 1 +

11 + 1 + 1 + 1

+ 11 + 1 x 0 +1 = 30

Are you ready for a fun challenge?

According to a study only 1% of people can see the animal hidden in the image below. This hypnotic image has been shared online but a lot of people: But can you spot the animal in the optical illusion?

Here is the image:

Can you see it?

Look again! Here is the shrunken image

Don´t get dizzy! You can step back from the image and look again!

So did you see the hidden panda in the picture? This optical illusion was created by Russian artist Ilja Klemencov to raise awareness about the endangered giant panda. As you may have seen, the image reveals the World Wide Fund for Nature´s (WWF) panda logo.

“While its numbers are slowly increasing, the giant panda remains one of the rarest and most endangered bears in the world,” WWF explained.

Share this optical illusion with your friends to see if they can spot it too!

From time to time one must take a break from obligations, routines, and the busy life in general. It can help to clear the mind – and recharge your batteries so you can jump head first into tomorrow’s challenges.

Mindteasers like crosswords, optical illusions, sudoku, and other puzzles make us exercise our brain in a way that offers a slightly different stimulus than when you sit and work at a computer all day.

I love to test myself in different ways. The best part is that it is both fun and healthy!

When my friends and I meet up for a cup of coffee or lunch, as a tradition we always test each other puzzles, challenges, riddles or similar. When you finally sort out who is the fastest one that day, you can move on to catch up and chit-chat!

This challenge my friend had when we met yesterday, it’s actually not as simple as it looks at first sight. Neither I nor our two other friends were right on our first attempt.
How many can you find?

Apparently, there is nothing strange about it – the vast majority of people get it wrong if they try to finish under 10 seconds, which is the time limit for this challenge!
Now we’ll see how it goes for you!

It is a yellow background image filled with lots of 7’s. But in a few spots, there are also a few hidden T’s. Because the number and the letter are so similar, this can deceive your eyes.
The question now is how many T’s can you find in the picture?!

Sure it’s a little tricky to find every single one, right?

Finding several T‘s is more difficult than you think. At least that was the case when I tried it.

Did you get it right?

Now, remember how many letters you found in the picture!

I can tell you that there are more than 5 T’s in the picture. Actually, quite a few more!

Okay, do you feel ready to see the answer? Below the picture, you can see if you got it right!

Time to check your answer! In the picture, we marked all T’s in white so you can compare!

The right answer is: there are 9 T’s in the picture!

Did you find over 5 T’s? Then you did a great job! Share this fun challenge with your friends!