If $\sqrt{784} = 28$, find the value of $\sqrt{7.84} + \sqrt{78400}$

If $\sqrt{784} = 28$, find the value of $\sqrt{0.0784} + \sqrt{0.000784}$

If $\sqrt{27.8} = 5.27$; the value of $\sqrt{2780}$ is:

1. 527

2. 52.7

3. 0.527

4. none of the above

n is the least natural number that must be added to 23 so that the resulting number is a perfect square, the value of n is:

1. 7

2. 2

3. 5

4. -7