The product of two consecutive odd numbers is 399. Find the lower of them.

(0.5 ×5 + 0.25 ×0.5 + 0.5 × 4 + 0.5 ×0.75) is equal to-

The sum of the digits of a 2 digit number is 9. When 27 is added to the number, the digits get interchanged. Find the number.

The number will be, whose square is equal to the difference between the squares of 975 and 585, is:

Let x be the least number of 4 digit that when divided by 2, 3, 4, 5, 6 and 7 leaves a remainder of 1 in each case. If x lies between 2000 and 2500, then what is the sum of the digits of x?

The arithmetic mean of the following data is .

23, 17,20,19,21

The value of $${3.157×4126×3.198\over63.972×2835.121}$$ is closest to : 

Select the number triad that is analogous to the given triads.
 (64, 8, 65), (125, 27, 89)