16 maths riddles only the smartest can get right

Whether you take maths classes regularly or it’s been a minute since you last quadraticked an equation, maths riddles are for everyone. From maths for adults (like calculating what time you need to start cooking if the turkey takes 40 minutes per kilogram and the guests arrive at 2 pm) to maths riddles for kids who like to have fun with numbers, maths is a part of all our lives. You don’t have to be a maths whiz to challenge yourself with these puzzles. We’ve ranked them from easy to hard, so you can warm up with some simpler maths riddles and end with the real head-scratchers. After all that number crunching, you’ll be ready for even more challenging riddles. There’s nothing like that “A-ha!” feeling when you crack a difficult riddle (or even an easier one), so let’s get started!

Using only addition, add eight 8s to get the number 1000.

Answer:

888 + 88 + 8 + 8 + 8 = 1000. This is the kind of number riddle you can work out with times tables, or by simple logic. First, get as close to 1000 as you can (888). From there, it’s easy to figure out the rest.

In reply to an inquiry about the animals on his farm, the farmer says: “I only ever keep sheep, goats, and horses. In fact, at the moment they are all sheep bar three, all goats bar four, and all horses bar five.” How many does he have of each animal?

Answer:

The farmer has 3 sheep, 2 goats, and 1 horse. You can solve this easy maths riddle with a quick hypothetical. Take sheep: we know that there are three animals that are goats and horses, so we suppose there are two goats and one horse. Checking this hypothesis gives us three sheep, which works out because there are four non-goats: three sheep, and one horse!

Test your logic skills with these 8 mind-bending puzzles. 

One brother says of his younger brother: “Two years ago, I was three times as old as my brother was. In three years’ time, I will be twice as old as my brother.” How old are they each now?

Answer:

One way to solve this maths riddle is to use even numbers: The older brother will be twice as old as his younger brother in three years’ time. This immediately rules out the older brother currently being 8, 11, and 14, so he must be 17, and the younger brother 7. Two years ago, they were 15 and 5 respectively, and in three years’ time, they will be 20 and 10.

Give your brain a workout by trying to solve these long riddles.

I add six to eleven, and get five. Why is this correct?

Answer:

This numbers riddle is designed to trip you up! You have to think more broadly. When it is 11 am, adding six hours makes it 5 pm.

Test your wits with our hardest riddles ever.

Old Granny Adams left half her money to her granddaughter and half that amount to her grandson. She left a sixth to her brother, and the remainder, $1000, to the dogs’ home. How much did she leave altogether?

Answer:

This one might have tripped you up! But the trick is not to focus on the hypothetical amounts, but on the fractions: Adding one half, one quarter, and one sixth tells us that the total is a fraction of twelfths (2+4+6=12). You can also think about it as 6/12, 3/12, 2/12, which equals 11/12. If the remainder is $1000, that must be one-twelfth, so the total is $12,000.

What single digit appears most frequently between and including the numbers 1 and 1000? Hint: look for a pattern!

Answer:

The most common digit is 1! Did you figure out why? Every number 1-9 appears exactly the same number of times in every ten numbers. But because we included the number 1000, there’s an extra occurrence of the number 1. In total, the number 1 appears 301 times, and every other number appears 300 times.

Need a laugh? Enjoy these 36 maths jokes for all number nerds. 

If a hen and a half lay an egg and a half in a day and a half, how many eggs will half a dozen hens lay in half a dozen days?

Answer:

Two dozen. If you increase both the number of hens and the amount of time available four-fold (i.e., 1.5 times 4 equals 6), the number of eggs increases 16 times. 16 x 1.5 = 24.

Master these 5 fun challenging brain teasers.

My twin lives at the reverse of my house number. The difference between our house numbers ends in two. What are the lowest possible numbers of our house numbers?

Answer:

These maths riddles aren’t easy to solve! The lowest possible numbers for the houses are 19 and 91. The difference is 72.

Heard of Pi? Here are 21 fascinating facts to add to your knowledge.

Three friends are on a road trip, and they rent a triple room for a night. When they get to the hotel, they pay the fee of $30 and go up to their room. The porter brings up their bags and refunds them $5 because the hotel is running a weeknight special. The three friends each keep one of the dollars and give the porter a $2 tip. Later, they sit down to work out their expenses for the weekend and find they have a problem.

They each paid $10 for the room and got $1 back each, making their contributions $9. Then they gave the porter a $2 tip. However, 9 times three is 27, plus two is $29. Where did the extra dollar go?

Answer:

This one is a bit twisty, but what it boils down to is that the three friends’ maths is wrong. They didn’t spend $29, they spent $27: $25 on the room, and $2 for the porter’s tip. The three remaining dollars were returned to them!