Show that 810 is not a perfect square.
 
 
Let us find the factorisation of 810.
 
Group the factors in pairs of two numbers
 
Then, 810 \(=\)

 
Here,
left over while grouping.
 
So, 810 is
perfect square.
Answer variants:
\(2\) and \(5\)
\((3 \times 3) \times (3 \times 3) \times 2 \times 5\)
\( 2 \times 3 \times 3 \times 3 \times 3 \times 5\)
not a