10 most difficult numbers riddles A list of numbers related questions that are most often answered incorrectly Numbers quiz Which of the following Roman numerals stands for 4?Both IV and IIII. Both notations are correct and historically Roman numerals were often written less consistently than today. The notation 'IIII' is often seen on clock faces. The reason for that may be practical, to avoid confusing the IV and VI when the clock is held upside down (although other theories also exist).very hard 25% IVIV72%IIIIIIII1%Both IV and IIIIBoth IV and IIII25%None of the aboveNone of the above1%Created by: globalquiz.org. Statistics based on 5390 answers in 4 languages »ancient Rome riddles » Which of the following is true for the solution with the pH=0?The OH − ion concentration is smaller than the H+ ion concentration. In chemistry, pH is a numeric scale used to specify the acidity or alkalinity of an aqueous solution. It is the negative of the logarithm to base 10 of the activity of the hydrogen ion .Traditionally the pH is being defined as: pH = - log10 [H+], where [H+] it is a H+ ions concentration in mol/dm^3 (M). So if pH = 0 this H+ ions concentration is 1 mol/dm^3 and the solution is strongly acidic.very hard 25% the OH − ion concentration is smaller than the H+ ion concentrationthe OH − ion concentration is smaller than the H+ ion concentration25%the OH − ion concentration is greater than the H+ ion concentrationthe OH − ion concentration is greater than the H+ ion concentration20%the OH − ion concentration is equal of the H+ ion concentrationthe OH − ion concentration is equal of the H+ ion concentration27%Such solution doesn't existSuch solution doesn't exist26%Created by: Paweł Kołodziejczyk. Statistics based on 2953 answers in 2 languages »mathematics riddles » Which numeral system was in use in ancient Sumer and Babilon?Sexagesimal. Remnants of highly composite sexagesimal system are in use even today for measuring angles, geographic coordinates and especially time. An hour of time is divided into 60 minutes, which in turn are divided into 60 seconds. very hard 31% octaloctal22%binarybinary20%decimaldecimal25%sexagesimalsexagesimal31%Created by: smyru. Statistics based on 11959 answers in 2 languages »ancient history riddles » Which currency was the first to be converted to decimal system?Russian ruble. The new ruble introduced with monetary reform of Peter the Great of 1704 was the first currency to be based on decimal system.very hard 37% American dolarAmerican dolar14%British pound sterlingBritish pound sterling23%frank of revolutionary Francefrank of revolutionary France24%Russian rubleRussian ruble37%Created by: smyru. Statistics based on 5403 answers in 2 languages »coins 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 14232 answers in 2 languages »calendar riddles » Which number is considered unlucky in East Asia?4. Words "four" and "Death" have very similar pronunciation in Chinese, Vietnamese, Korean and Japanese. In East Asia many buildings do not have a 4th floor. Some high-rise residential buildings omit all floor numbers with "4", e.g., 4, 14, 24, 34 and all 40–49 floors. hard 49% 3321%4449%121222%40406%Created by: Sumit Tamang. Statistics based on 10239 answers in 4 languages »South Korea riddles » What is the sum of all the numbers on the roulette wheel?666. This fact contributed to the naming of the game as Satan one, since 666 it is called the number of the beast by the Book of Revelation.hard 50% 6006008%66666650%78378324%1000100016%Created by: smyru. Statistics based on 6490 answers in 2 languages »games riddles » How many players of one team are there in a pool during the water polo game?7. A team consists of 6 field players and one goalkeeper in the water at any one time. hard 52% 5534%7752%998%11114%Created by: Paweł Kołodziejczyk. Statistics based on 9345 answers in 2 languages »water riddles » Which of the following numbers is the greatest?1/3. Quite surprisingly, most players answer that both answers 1/3 and 33% are correct. But 1/3 is more than 33%. (it is 33.3333333...)hard 53% 1/31/353%0,30,34%33%33%8%Both answers 1/3 and 33% are correctBoth answers 1/3 and 33% are correct33%Created by: globalquiz.org. Statistics based on 18171 answers in 2 languages »mathematics riddles » What is the volume of a soap bubble with radius R=1 cm?4/3π cm3. Equation for the volume of a sphere: 4/3πR^3.hard 59% 3/4π cm33/4π cm319%4/3π cm34/3π cm359%4,3π cm34,3π cm39%It isn't possible to calculateIt isn't possible to calculate12%Created by: Paweł Kołodziejczyk. Statistics based on 12870 answers in 2 languages »geometry riddles » Play numbers quiz and see all the questions.