So Rituparna tries to prove to him his abilities and he says, see that tree there, I can estimate how many leaves there are on that tree by counting leaves on one branch.

所以睿都巴若那就试图证明自己的能力,他说,看那边的树,我只需数一根枝杈上的叶子,就能估算出树上叶子的总数

耶鲁公开课 - 金融市场课程节选

You have n branches on the tree and you count the number of leaves and sum them up.

一共有n根树枝,你数了叶子的数量然后把他们加起来

耶鲁公开课 - 金融市场课程节选