Book Maths Puzzle

Q. All the nine digits are arranged here so as to form four square numbers: 9, 81, 324, 576.
How would you put them together so as to form a single smallest possible square number and single largest possible square number?

Read Solution (Total 3)

Book Other Question

I just have a doubt please reply my question is while finding envelope of a curve why should we differentiate the equation partially with respect to the parameter and equate it to 0 if anybody knows please clear my doubt
Q. If 4 whole number are taken at random and multiplied together , what is the probability that the last digit in the product is 1,2,7 or 9?

Option
a)15/653
b)12/542
c)16/625
d)17/625
please explain the numerical
answer is (c)