Now, it depends on whether you want to simplify this to the smallest possible radicand yet leave the answer in exact form, or if you want a numerical approximation of the value of
The numerical approximation is easy. Punch 140 into your calculator and then press the square root key. Round off appropriate to your application and you are done.
To simplify, you need to find the prime factorization of the radicand.
Divide 140 by 2, you get 70
Divide 70 by 2, you get 35
35 is not divisible by 2
35 is not divisible by 3
Divide 35 by 5, you get 7 which is prime.
So your prime factorization is 2 * 2 * 5 * 7.
You have one pair of factors, namely the 2s. Eliminate both 2s from under the radical, and take one of them outside the radical. That leaves you with a 2 outside the radical and 5 * 7 = 35 still inside, hence your answer is