how to make button align center in div code example

Example 1: html center button

button{
    /*Change the width as much as you like, but make sure 
    margin-left and margin-right + width = 100%*/
    width:50%;
    margin-left:25%;
    margin-right:25%;
}

Example 2: how to make a button centered in html5

<!--Put the button inside a p like this-->
<p style="text-align: center;"><button>See?</button>Whatever</p>