A 1200 kg satellite is in a circular orbit 900 km up…

Step 1. From orbit. $\dfrac{GMm}{2r} = \dfrac{4.014 \times 10^{14}\ \text{m}^3/\text{s}^2 \times 1200\ \text{kg}}{2 \times 7.3 \times 10^{6}\ \text{m}} = 3.30 \times 10^{10}\ \text{J}$.

Step 2. From the ground. $\dfrac{GMm}{R} = \dfrac{4.014 \times 10^{14}\ \text{m}^3/\text{s}^2 \times 1200\ \text{kg}}{6.4 \times 10^{6}\ \text{m}} = 7.53 \times 10^{10}\ \text{J}$.