The area of the shaded region within the square $ABCD$ is . . . . . . $cm^2$. (Assume the side of the square is $28 \ cm$ and it contains four identical circles).

If the area of a triangle with base $x$ is equal to the area of a square with side $x,$ then the altitude of the triangle is

$A$ parallelogram has sides $60\, cm$ and $40\, cm$ and one of its diagonals is $80\, cm$ long. Its area is

Find the number of bricks,each measuring $25\, cm \times 12.5\, cm \times 7.5\, cm$,required to construct a wall $12\, m$ long,$5\, m$ high,and $0.25\, m$ thick,if the sand and cement mixture occupies $5\%$ of the total volume of the wall.

If the radius of one circle is $12$ times the radius of another,how many times does the area of the greater circle contain the area of the smaller circle?

$A$ steel sphere of radius $4 \, cm$ is drawn into a wire of diameter $4 \, mm$. Find the length of the wire in $mm$.