Direction : What value should come in the place of question mark (?) in the following questions?

1798 ÷ 31 × ? = 348

The distance between the center of two equal circles each of radius 3 cm, is 10 cm. The length of a transverse common tangent is 

The value of $${\sqrt{40+\sqrt{9\sqrt{81}}} }$$ is

If the angles of a triangle are in the ratio of 2:3:7, then find the ratio of the greatest angle to the smallest angle.

The value of 64 ÷ 2 ×(9÷3) ×3÷9-32 is:

If ' n ' be any natural number , then by which number ( n⁴-n ) is always divisible ? 

X can do a piece of work in 24 days. When he had worked for 4 days, Y joined him. If complete work was finished in 16 days, Y can alone finish that work in :

The angle of elevation of ladder leaning against a house is 60° and the foot of the ladder is 6.5 meters from the house. The length of the ladder is