How much is 1 third of 21?

What is the multipliable inverse of 1? How many significant figures does 13436.0 mm have? Can two math terms be separated by a multiplication sign? What is separated by a plus or minus sign and can be a number or a product of a number and variables? Are the diagonals of a parallelogram parallel? What are all the shapes that are not polygons? Why are snakeheads called that? How do you determine the maximum and the minimum values possible for the actual width and length of the book cover? 127 as a decimal in millimeters? How many sixth would be the same as three third? What is 6.052 rounded to the nearest hundredth? What is 60 over 144 in simplest form? What type of conic is created by 4x-5y plus x squared plus 2y squared equals 0? Why was Ada lovelace famous? Is a negative number in parentisis and negatie or positive number? Which letter in the alphabet has only one pair of perpendicular lines? What is 52 multiplied by 1.56? How many times does 1 go into 27? What is the volume of a rectangular prism height is 9 centimeters and the length width of whose base are 4 centimeters and 7 centimeters respectively? What is l988 in Roman Numerals?