I guess finding the approximate value

Question

Suppose a classmate tells you that 3 square root of 6≈2.5. Without a calculator, how can you convince your classmate that he or she must have made an error?

Answer 1

2 < sqrt(6) < 3 because 2^2=4 < 6 < 9=3^2

Next,

multiplies everything by 3:

6 < 3 * sqrt(6) < 9

So there is no way 3 * sqrt(6) can be 2.5

Note that sqrt(6) is ABOUT 2.4494897427831780981972840747059‬