Here's the breakdown:

* Speed of Light: Radio waves travel at the speed of light, which is approximately 299,792,458 meters per second (186,282 miles per second).

* Time Elapsed: Since 1887, approximately 136 years have passed.

* Distance Traveled: Multiplying the speed of light by the time elapsed gives us a distance of approximately 4.06 x 10^16 meters or 2.52 x 10^16 miles.

Therefore, the first radio waves have traveled about 40.6 quadrillion meters or 25.2 quadrillion miles into space.

Important Note: This is just a theoretical calculation. The actual distance the first radio waves have traveled could be slightly different due to various factors such as the specific direction of the transmission and the scattering of the waves as they propagate through space.