How many three-digit numbers are there in which all the digits are odd? 

What approximate value should come in the place of question mark (?) in the following question?
 (8423 + 3120 + 6543) ÷ (1536 + 377 + 189) = ?

Find the sum of all prime numbers between 10 and 90.

Direction: what should come in place at question mark(?).

(0.85% of 405) +(2.25% of 550)=?

The average age of 24 boys and their teacher is 15 years. When the teacher's age is excluded, the average age decreases by 1 year. The age of the teacher is: 

The ratio of the radii of two wheels is 3: 4, then the ratio of their circumferences will be.

What is the minimum number of square marbles required to tile a floor of length 5 meters 78 cm. and width 3 meters 74 cm?  

The area of a triangle with vertices A (0, 8), O (0, 0), and B (5, 0) is :