`const`

declares a constant value.

A `const`

statement can appear anywhere a `var`

statement can. Constant
expression perform arithmetic with arbitrary precision. A numeric constant has
no type until it's given one, such as by an explicit conversion.

A number can be given a type by using it in a context that requires one, such as a variable assignment or function call.

```
package main
import (
"fmt"
"math"
)
const s string = "constant"
func main() {
fmt.Println(s) // constant
const n = 500000000
const d = 3e20 / n
fmt.Println(d) //6e+11
fmt.Println(int64(d)) //600000000000
fmt.Println(math.Sin(n)) // -0.28470407323754404
}
```