Directions(Q.16 to Q.25 ):

If ${(78)^2}$ is subtracted from the square of the number, the answer so obtained is 6,460.What is the number?

Let the number be x.

According to the question,

${x^2} - {78^2} = 6460$

$Rightarrow {x^2} = 6460 + 6084$

$Rightarrow {x^2} = 12544$

$Rightarrow x = sqrt {12544} = 112$