Yeah it was his moment of "HOLY SMOKES I ACTUALLY DID MATH"0
Maybe he is reminded of something from his previous life??? ╮(￣▽￣)╭
He is enlightened. He managed to realize that by using imagination finger, he can count a greater numbers if his finger is not enough to count. Like, he see his finger shows 3, but he know that the count is 13 because he used lippe's finger for the 10 count.
So, for the question before which is 6+8, he realize he can start by imagining lippe's finger as 6, and he just have to use his finger for 8, and start counting from 7 on his finger.
why was he looking at his fingers again? me confused? Σ(っ°Д °;)っ