A calculator is a device for calculations in math. 计算器是数学上用于计算的工具。

　　It is not a computer. 它不是计算机。

　　And it is usually small, digital and inexpensive. 它通常是小巧且廉价的电子产品。

　　Many students use calculators for their school work. 许多学生用计算器做作业。

　　The first pocket-size calculator appeared in about 1970 around the world. 世界上第一款袖珍计算器大约出现在1970年。

　　Because it was powered by batteries, it was portable, handy and very convenient. 因为计算机是电池充电，所以它可移动，非常方便快捷。

　　However, it was very expensive. 然而，当时计算器很贵。

　　It cost almost 400 $. 它的价格约是400美元。