There's no better way to keep your mind sharp during these lockdown days than with a few good brain teasers, puzzles, optical illusions, and riddles.

Here are a few great little head-scratchers to keep you busy. If you can get all of them right without having to check the answers then we salute you for your brilliance.

**RELATED: 11 SPOOKY OPTICAL ILLUSION TRICKS OUR MIND CREATES**

Some of these brain teasers are pretty tricky, but if you want to go to the next level you might also want to try your hand at these viral math equations. Let's get started.

## 1. Bridging the ditch

Here's a bit of a head-scratcher, though it's a fairly easy brain teaser to get us started. This brain teaser is taken from Henry Ernest Duduney's 1907 book 'Canterbury Puzzles', simplified by us into modern English.

*"I thought I was finally free, but I had forgotten that I still had to cross a deep ditch before I could really escape.*

*"The ditch was 10 feet wide, I could not even attempt to jump it, especially as I had sprained my ankle in the escape attempt.*

*"Looking around for a tool that could help in my escape I found eight narrow planks of wood lying together in a pile. With only these, and the planks were each no longer than 9 feet long, I finally managed to escape by making a bridge across the ditch.*

*"How was this done?"*

## 2. The fork in the road

As we're still easing into things, here is a well-known logic question. If you haven't heard of it, give it a go.

*You need to get to a nearby village, and you get to a fork in the road. You know that one route will take you to the village and the other will take you down a treacherous terrain where you could very easily fall off the edge of a cliff. *

*Thankfully, two twins are at the fork in the road to help you, one on the left and one on the right. The trouble is, one always lies. You can ask them each one question. What do you ask to make sure you know the correct direction of the village?*

## 3. Which square is darker?

A simple optical illusion brain teaser. Can you correctly state which of these squares is darker than the other?

## 4. The timepiece brain teaser

Did you know that timekeeping allowed early seafarers to find their way like never before and spurred on a new age of exploration? Now that we've got that magnificent piece of maritime trivia out of the way, here's a timepiece riddle.

*The sundial has the fewest moving parts of any timepiece.*

*Which manmade timepiece has the most moving pieces?*

## 5. What am I?

Riddle me this. This shouldn't be too difficult, seeing as teacher Bret Turner set this brain teaser as the 'Puzzle of the Week' for his young students.

## 6. The photograph conundrum

Another in the long list of classic brain teasers, this one might be well-known. If you don't know the answer already, give it a go.

*A man is looking at a photograph of someone. His friend asks who it is. The man replies, “Brothers and sisters, I have none. But that man’s father is my father’s son.” Who was in the photograph?*

## 7. How many triangles in the image?

This puzzle was posted by Sky News reporter, and erotic romance novel writer, Kay Burley on her Twitter.

Needless to say, the comments section was full of different answers, and different justifications for each answer.

## 8. Can you solve this "open the lock" puzzle

We're getting to the harder brain teasers now. Here's the puzzle:

**682**: One digit is right and in its place**614**: One digit is right but in the wrong place**206**: Two digits are right but both are in the wrong place**738**: All digits are wrong**380**: One digit is right but in the wrong place

*Can you get the right code based on these instructions?*

And here's a tip to get you started. We suggest starting with getting rid of the 7's, 3's and 8's, first seeing as all of these digits are wrong.

## 9. What do all of these words have in common?

What do the following words have in common?

*Grammar, banana, revive, voodoo, potato, dresser, uneven.*

Here's a cryptic little tip: take a long hard look at them, from one end to the other.

## 10. How many girls are there in the photo?

This photo was posted by photographer Tiziana Vergari as part of an Instagram competition called the Weekend Hashtag Project, in which photographers had to submit photographs under the theme of 'identity.'

Aside from being a great photograph, it's also a brain teaser, as the many commenters later pointed out.

Without getting philosophical — we don't want to know how many metaphorical versions of their own identities the girls might be seeing — can you say how many girls are in the photograph?

## 11. Going back in time

Here's an intriguing little riddle.

*A person is born in 2020 but died in 1950. How is this possible?*

How indeed. And no, time travel isn't an option. Nor is some weird Benjamin Button scenario where a person is born that ages backward.

## 12. How far can you get with 50 motorcycles

Now we're at the really tricky ones. This brain teaser was actually a riddle asked by Adobe employers to prospective engineers in job interviews.

So here it is:

*You have 50 drivers on 50 motorcycles that can each go 100 kilometers. What is the farthest distance you can travel to?*

## 13. A gangster kidnaps you and wants to play a little Russian roulette...

Here's a slightly morbid question that we've adapted from a brain teaser Facebook asked prospective employees in job interviews:

*A gangster kidnaps you. He likes messing with people, so he puts two bullets in consecutive order in an empty six-round revolver, spins it, points it at your head, and shoots.*

**click* You’re still alive.*

*But he's not done. *

*This gangster's into probability puzzles — maybe he had higher aspirations before circumstance dealt him an ugly hand in life. *

*He asks you, “do you want me to spin it again and fire or pull the trigger again right away?” For each option, what is the probability that you’ll be shot?*

*Answers below:*

*1. Bridging the ditch*

*The solution to this brain teaser is best explained by the illustration below. If the fugitive had placed his eight planks, in the manner shown, across the angle of the ditch, he would have been able to cross without much trouble. *

*2. The fork in the road*

*Ask each individual what the other would say. The honest twin, knowing his twin is a liar, would tell you the other's lie. The lying twin would tell you his lie. So whatever answer they give, take the other road.*

*3. Which square is darker?*

*"Can you correctly state which of these squares is darker than the other?" *

*No, you actually can't, as they are both the same color. This is known as the checker shadow illusion, created by Edward H. Adelson.*

*The fact that square B is surrounded by darker squares, and is contextualized as a light square on the board means your brain is tricked into thinking it is lighter than square A. The shadow cast by the green cylinder also makes square B darker than it would otherwise appear.*

*4. The timepiece puzzle*

*The manmade timepiece with the most moving pieces is the hourglass, with its thousands of moving grains of sand.*

*5. What am I?*

*The answer is the letter 'E'. The word 'Everything' begins with 'E'. 'Everywhere' ends with 'E'. 'Eternity' begins with 'E', and the phrase 'Time and Space' ends with 'E'. *

*Have a read here to see how one of teacher Bret Turner's students gave an alternative, spiritual, response that went viral.*

*6. The photograph conundrum*

*His son.*

*7. How many triangles in the image*

*The answer is 40. *

*The grid is made up of 16 individual triangles — four in each quarter. These triangles make up eight bigger ones — two in each quarter. These, in turn, form four even bigger ones that configure two larger ones.*

*So the answer 40 can also be found with the equation 16+(8x2)+(4x2)+(1x2)+(1x2).*

*8. Can you solve this "open the lock" puzzle*

*The code is 042. Have a look here to see an in-depth explanation of how to get to that answer.*

*9. What do all of these words have in common?*

*If you take the first letter of each word and place it in the end, it will spell the same word backward.*

*10. How many girls are there in the photograph*

*There are 2 girls in the photograph. Back to back mirrors create the illusion that there are more.*

*11. Going back in time*

*The person was born in 2020 B.C.*

*12. How far can you get with 50 motorcycles?*

*The simplest answer to this brain teaser would be to say 100 kilometers, but that would be incorrect. *

*You can also drive all of the motorbikes together to a location 50 kilometers away from the starting point. *

*Then, take all of the gasoline from half of the bikes, and pour it into the other half. Now you have 25 bikes with full tanks.*

*Travel another 50 kilometers, and repeat. Using this method you can travel a total of 350 kilometers.*

*However, this is the best solution:*

*Vacate the tank of a bike as soon as there is the capacity for fuel in any other bike — so don't wait for 50km. After 2km each bike will have 98km of fuel left.*

*So divide what's left in one bike into the other 49 bikes (49*2 = 98).*

*Again travel a distance of 100/49km. That will be sufficient to vacate the fuel of one more bike into the remaining 48 bikes.*

*So the correct answer is sum 100/(x) from 1 to 50, dividing fuel from motorbikes to the others.*

*This allows a travel distance of 449.92 km.*

*13. A gangster kidnaps you and wants to play a little Russian roulette...*

*The key hint is that the bullets were loaded consecutively, so they'll be next to each other in the cylinder.*

*There are 4 ways to arrange the revolver with consecutive bullets so that the first shot is blank. Here are the possible scenarios:*

*(xBBxxx)**(xxBBxx)**(xxxBBx)**(xxxxBB)*

*The other two scenarios would have meant you got shot on the first attempt: (BBxxxx) or (BxxxxB).*

*If we look at scenarios 1-4 above, your odds of getting shot are 1/4 or 25%. (Only scenario number 1 would get you shot).*

*However, if you respin, there are 2 bullets remaining and 6 total slots. 2/6 or 33%.*

**Editor's Note 05/06/20:** One of our readers kindly pointed out that there was a better solution to question 12. We have edited the article to add this in.