* Know the prefixes:

* Tera (T) = 10^12

* Nano (n) = 10^-9

* Set up the conversion:

650 terameters * (10^12 meters / 1 terameter) * (10^9 nanometers / 1 meter)

* Simplify:

650 * 10^(12+9) nanometers

650 * 10^21 nanometers

* Result:

6.5 x 10^23 nanometers

Therefore, there are 6.5 x 10^23 nanometers in 650 terameters.