Ballpark — July 23, 2026
Answers to that day's 5 daily estimation questions.
About what is the diameter of a tennis ball?
~6.7 cm
A tennis ball is a bit under 3 inches across.
People who climb Mount Everest each year
800 people
Congestion is becoming a major safety issue.
Distance light travels in a single nanosecond
12 inches
Light is incredibly fast, but not instantaneous.
Height of a giraffe
18 feet
The tallest land mammals.
GDP of the world
100 USD (trillions)
Crossed the 100 trillion mark recently.