10 most difficult math riddles A list of math related questions that are most often answered incorrectly Mathematics quiz Augustus was born on 1 January 10BC. Which birthday did he celebrate at 1 January 10AD?19. There was no year number zero. There were only 1999 years between 1000BC and 1000AD.very hard 38% 191938%202037%212119%80805%Created by: Gizem İsmailoğlu. Statistics based on 17160 answers in 4 languages »calendar riddles » Typically, how many leap years are in a century?24. The Gregorian Calendar omits 3 leap days every 400 years, omitting February 29 in the 3 century years (integer multiples of 100) that are not also integer multiples of 400. For example, 1600 was a leap year, but 1700, 1800 and 1900 were not. Similarly, 2000 was a leap year, but 2100, 2200, and 2300 will not be.hard 42% 20209%242442%252544%1001004%Created by: ex-terminator. Statistics based on 15092 answers in 2 languages »numbers riddles » If Earth's radius was larger by 1 meter, how much longer would its equator be?By approx 6 meters. For each circle, the length of the circumference is c=2πr. Hence, if a radius grows by 1 meter, the circumference grows by 2 π meters - no matter what the initial value of radius was.hard 45% by approx 6 metersby approx 6 meters45%by approx 6 kilometersby approx 6 kilometers18%by approx 60 kilometersby approx 60 kilometers21%by approx 6000 kilometersby approx 6000 kilometers15%Created by: SpikeMe. Statistics based on 27114 answers in 2 languages »Earth riddles » Which famous scientist was born on the Pi day? (March 14)Albert Einstein. 14 of March is celebrated on many schools and universities as both Pi Day and the birthday of Albert Einstein. On of the traditions is the 'Pi Pie' (pictured).hard 46% Albert EinsteinAlbert Einstein46%Blaise PascalBlaise Pascal18%Isaac NewtonIsaac Newton16%all of the aboveall of the above17%Created by: globalquiz.org. Statistics based on 12504 answers in 4 languages »scientists riddles » How many possible code combinations are there for this kind of lock?10000. The possible codes are from 0000 to 9999 inclusive. There are 10 possibilities for each ring, thus there are 10*10*10*10 possible codes.hard 52% 9999994%100010006%9999999936%100001000052%Created by: Teddy. Statistics based on 13805 answers in 2 languages »bicycles riddles » Which of the following is a prime number?16769023. A prime number has no positive divisors other than 1 and itself. Hence, a prime bigger than 2 cannot be even. All prime numbers bigger than 5, written in the usual decimal system, end in 1, 3, 7, or 9. average 67% 23882990238829909%167690231676902367%38377296383772968%117238351172383515%Created by: Sumit Tamang. Statistics based on 17425 answers in 2 languages »mathematics riddles » How many edges does a Möbius strip have?One. The Möbius strip is a surface with only one side and only one boundary component (edge). A line drawn starting from the seam down the middle will meet back at the seam but at the "other side". If continued the line will meet the starting point and will be double the length of the original strip.easy 72% oneone72%twotwo18%threethree4%fourfour3%Created by: globalquiz.org. Statistics based on 16142 answers in 4 languages »geometry riddles » Let's say the stock price was 10 two days ago. It has dropped by 50% yesterday and raised by 50% today. What is the stock price now?7.5. Stock price was 10 two days ago. Yesterday it dropped by 50% to 5. Today it raised by 50% (of 5) to 7.5easy 74% 101012%12.512.510%7.57.574%20201%Created by: globalquiz.org. Statistics based on 13067 answers in 2 languages »economy riddles » How many edges does a cube have?12. A cube has six square faces, each of which has four edges - but each edge is shared with another face.very easy 80% 441%889%121280%16168%Created by: globalquiz.org. Statistics based on 24633 answers in 2 languages »geometry riddles » Play mathematics quiz and see all the questions.