A ballpark figure is a rough numerical estimate or approximation of the value of something that is otherwise unknown. ... A salesperson could use a ballpark figure to estimate how long a product a customer was thinking about buying might be viable.

How do you write a ballpark estimate?

For example, a student is give the number 21 and 39 and directed to make a ballpark estimate. They first must know 21 is between the benchmark numbers 20 and 30, but closer to 21, and 39 is between 30 and 40 but closer to 40. So 21 + 39 =? 20 + 40 = 60!

Why is it called a ballpark estimate?

The origin of this phrase comes from how a commentator would give an estimate of the number of audiences by just looking around. Speculated to have started in America through baseball but it is now a popular way of speaking throughout the world.