11 Mind-Bending Puzzles With Surprisingly Simple Answers

It’s time to get your brain juices flowing. Teasers are the perfect way to sharpen your mind, whether for children or adults, especially the math ones. When solving, try to time yourself to see how fast you got the answer, or better yet, grab a friend and see which one of you will solve each puzzle first!

1. This one’s a real headscratcher. You can’t cross the equal sign!

Answer: Create an angular line on the first plus sign to make it a 4. Thus, the equation will be:
545 + 5 + 5 = 555

2. Change your perspective.

Answer: Realistically, the answer should be 17. But here, it’s 5 because it’s applied in a time context. So, 17:00 is actually 5 o’clock.

3.

I am an odd number. Take away a letter and I become even. What number am I?

Answer: Seven, because if you take away the “s,” it’s “even.”

4. Two apples, three people, one slice...

Three friends want to share two apples and get the equal amount. But, you only get one slice. How will you divide the two apples equally among the three friends?

Answer: Put both apples next to each other and slice 1/3 of both fruits together. That leaves two 1/3 of the apples for one friend and two 2/3 of the apple for the remaining two friends.

5.

Three friends check into a hotel room that costs $30. Each friend pays $10. The Hotel Manager realizes that the room is actually for $25 and gives back $5 to the bellboy so he could return the amount.
The bellboy takes $2 to himself and gives back $1 to each friend, making every person pay $9, totaling to $27. The bellboy took $2 so that adds up to $29. Where’s the extra dollar?

Answer: Don’t count the bellboy’s $2, since it’s already added to the $27. So, the amount is $27 from all the friends including the bellboy’s $2, leaving the 3 $1s as a refund to every friend.

6.

A bat and a ball both cost a total of $1.10. The bat costs $1 more than the ball. How much does the ball cost?

Answer: The ball costs $0.05, because the bat costs $1.05. (0.05 + 1.05 = 1.10)

7.

A bunch of flowers doubles in size every day. On the 20th day, they cover the entire pond. On what day was the pond half-covered?

Answer: The 19th, because it doubles every day, and on the 20th day it doubled to cover the entire pond.

8.

You have 8 identical-looking marbles, but one of them is heavier than the rest. You have a comparison scale that can weigh marble(s) against each other, but you can only use it twice. How are you going to figure out which marble is the heavy one?

Answer: Take aside 6 marbles and weight three against the other three. If they’re both the same weight, weigh the two remaining ones to find which is the heavier marble.
If one of the two three-marble batches is heavier, take the side that weighs the most and weigh two of the marbles against each other to find the heavy marble. If they’re both the same weight, that leaves the third marble as the heavy culprit.

9.

A father is four times as old as his son. In 10 years, he will be twice as old as his son. How old are they now?

Answer: The son is 5 while the father is 20 (Mathematically correct, but biologically unusual!) Why?

Let son’s current age = S, then father’s current age = 4S.
In 10 years:
Son’s age = S + 10
Father’s age = 4S + 10

According to the problem:
4S+10=2(S+10)

Solve:
4S+10=2S+20
6S=30
S=5

10.

Answer: Grandpa is bald.

11.

Answer: The doctor is his mom.

Brain-teasers remind us that the simplest questions can hide the cleverest twists! Did one of these riddles stump you, or did you solve them all? Share which puzzle tricked you most in the comments—or tag a friend to test their logic with the toughest one. Keep challenging your mind with more puzzles.