1 . She carries a pocket ________ (calculate) everywhere to make a calculation. (所给词的适当形式填空)

2 . You can use a ______________to ______________the average mark of the class and then your______________ can be accurate.(calculate) (所给词的适当形式填空)

3 . A pocket ________ (计算器) only works to eight decimal places. (根据汉语提示单词拼写)

4 . Scientists produced the world’s first pocket ________(计算器) in 1972. (根据汉语提示单词拼写)