wangweicalc v1.0.3

let obj = require('./index.js) obj.sum (num1,num2)

eg: obj.sum(1,2) // 3

obj.subtrac(num1,num2)

eg: obj.subtrac(1,2) // -1

obj.multip(num1,num2)

eg: obj.multip(3,2) // 6

obj.divis(num1,num2)

eg: obj.divis(4.2) //2