For a velocity, V that is a significant fraction of light-speed (c), the energy needed to reach the velocity v

For a velocity, V that is a significant fraction of light-speed (c), the energy needed to reach the velocity v is approximately 10 to the 23rd power joules/[1 - (V/c)]. How does the energy required to reach 99% of light-speed (V/c = 0.99) compare (USE A RATIO) with the amount needed to reach 50% of light speed (V/c = 0.50)?