







Could you tell me the name for the bar in a division problem? 
19961021 

Linda pose la question : Could you tell me the name for the bar in a division problem. Not the line with dots on either side but the line that divides the two numbers? My name is Linda. I am asking for my niece who is in 8th grade. Chris Fisher lui répond. 





What is the volume of a regular tetrahedron? 
19961021 

Paul Bleier pose la question : How does one calculate the volume and the height of a three sided pyramid formed by equilateral triangles? Bruce Gilligan lui répond. 





How many digits are there in 2^2520? 
19961007 

Rita Leung pose la question : A)The number 64 is a sq., a cube, and a sixth power because 64=8*8, 4*4*4, 2*2*2*2*2*2. Find the smallest integer greater than 1 that is a sq., a cube, a 4th, 5th, 6th, 7th, 8th, 9th and 10th power. I have found that the answer is 2 to the power 2520th. B) How many digits are in the correct answer to part A? The answer is uncertain. It is either 758 or 759. Can you give me any ideas? Penny Nom lui répond. 





Why is lbs the abbreviation for pounds? 
19961003 

Nancy Mutdosch pose la question : What does lbs stand for? Why is it the abbreviation for pounds? Chris Fisher lui répond. 





Why is a circle divided into 360 degrees? 
19960930 

Kurtis Kredo pose la question : I was recently wondering why a circle has been divided in to 360 degrees. When I asked my physics teacher he could not think of an answer. His guess is that it probably has to do with people long ago using the base 6 number system. I have a small inkling that it has to do with easy conversion or usage with radians or grads. Chris Fisher lui répond. 





Divisibility of 2n choose n. 
19960924 

Kathy Doan pose la question : Can you prove that "2n choose n" is not divisible by 3, 5, and 7 for infinitely many n? Penny Nom lui répond. 





How many possible combinations of answers are there? 
19960920 

David Bester pose la question : Suppose there is a 12 question test. Each question can be answered only by true or false. Assuming that all questions are answered (i.e. none are left blank), how many possible combinations of answers are there? And what formula was used to arrive at the answer? Denis Hanson lui répond. 





Term definitions 
19960918 

M. Seltzer pose la question : A 7th grade algebra student would like the definition of the terms proper factor and perfect number. The Centralizer lui répond. 





How do you find out if a number is a composite or prime? 
19960916 

Trish Feenstra pose la question : Hi my name is Trish Feenstra. In grade 8. How do you find out if a number is a composite or prime if it is big like 37 529? Reply soon got a test on Friday the 13th Denis Hanson lui répond. 





Repeating decimals 
19960909 

Alice pose la question : What is the line called that is placed over the decimal to show that it is infinitely repeating? The Centralizer lui répond. 





Will this always yield a palindrome? 
19960828 

Andy Golden pose la question : My friend Justin Skywatcher, said that when his children were in 6th grade, they were taught that if you take any number, reverse it and add the two together, a palindrome will result. If not, continue performing the above operations, and a palindrome will eventually result. Will this always yield a palindrome? Chris Fisher lui répond. 





Thousands, millions, billions and trillions 
19960822 

Blaine pose la question : What are the names of the periods in groups of numbers like 123,456,789. I need to know the names of them for school. I already know the first ones: units thousands millions billions trillions. Penny Nom and Diane Hanson lui répond. 





Where do 2^x and x^2 intersect? 
19960723 

Darin M Selfridge pose la question : The intersecting points of y=2^x and y=x^2, graphed along with x^2=2^x, are obviously three... (2,4), (4,16) and (?,?). I am having problems figuring out the value, and even an equation for the (?,?). Can you help? Harley Weston Chris Fisher lui répond. 





How do you raise a number to an imaginary/complex power? 
19960703 

Andy Golden pose la question : How do you raise a number to an imaginary/complex power? I know how you raise "e" to a complex power, like e^(pi*i): cos pi + i * sin pi But what about numbers other than "e"? What if I want to raise 5 to the 2i power? How is that done? Chris Fisher lui répond. 





What are fractals and are they of any practical use? 
19960626 

Ron Lewis pose la question : What are fractals and are they of any practical use? Chris Fisher lui répond. 

