บท 100: Chilies from a Foreign Land

She could gauge Liang Chengcai's knowledge.

"Very good, you got the basics down. Then we can learn the vertical form today."

Then, Lin Xiaoyue taught the vertical method of addition and subtraction to Liang Chengcai.

Liang Chengcai was very surprised. He didn't expect that he could calculate the addition or subtraction of two big numbers so quickly without using an abacus.

"Well, now that you've learned addition and subtraction, let's learn compound addition and subtraction using brackets."

Lin Xiaoyue wrote down an equation and began to talk about the calculation method and the use of brackets.

Liang Chengcai was pleasantly surprised again.

"The emergence of compound addition and subtraction allows us to use simple methods to find the sum or the difference." Lin Xiaoyue said.