"Renshu, quick, help me write this down. Let's calculate together.
"Calculate multiple times, don't make any mistakes.
"The data from the computer before mentioned that the urban road density is about 3km/square kilometer, so for a 700 square kilometer city, the urban roads are approximately... 2100 kilometers.
"As for the streetlight spacing, it should be at least over 20 meters, right? 20 to 50 meters? Let's use an average of 30 meters. Assuming there are streetlights on both sides of the road, this would be... 140,000 streetlights.
"The question mentioned that each streetlight has a power of 150W, but we also have to consider the average daily lighting time. Let's calculate it as 10 hours.
"Multiply these two, and that's the final answer.
"... approximately 210,000 kilowatt hours."
Without a calculator, the two could only do the math mentally, so they were afraid of making mistakes and each calculated a few more times.
