What would be the smallest natural number which when divided either by $$20$$ or by $$42$$ or by $$76$$ leaves a remainder of $$7$$ in each case?

Find the smallest number $y$ such that $y \times 162$ is a perfect cube.

The probability that a $k$-digit number does NOT contain the digits 0, 5, or 9 is :

A cube is built using $$64$$ cubic blocks of side one unit. After it is built, one cubic block is removed from every corner of the cube. The resulting surface area of the body (in square units) after the removal is __________ .