Shorter hands

Hi - I have an array with some objects in them.

I want to shorten what im doing here in my code - can anyone help ‘reduce’ it for me…

var obj = {
number:1
}
var ary = [obj];
// that cool above - i wnat to streamline whas below..
var n = ary[0].number - 0.1;
ary[0].number = n;

console.log(n);

easy!?