第 45 课: 各种运算：加，减，乘，除-5

Twelve divided by two equals six. 十二除以二等于六

Two times six equals twelve. 二乘六等于十二

Six divided by three equals two. 六除以三等于二

Two times eight equals sixteen. 二乘八等于十六

Ten divided by five equals two. 十除以五等于二

Fifteen divided by five equals three. 十五除以五等于三

Twenty divided by five equals four. 二十除以五等于四

Four times five equals twenty. 四乘五等于二十