Add random number at Random time intervals

The thing is i want to add random number to a variable which is initially 0 which has to happen after a random timoeut until the variable reaches 100.

$scope.var1 = 0;

do{
    $timeout(function(){
        $scope.var1 += Math.floor(Math.random * 100 +1);
    },Math.floor(Math.random * 100 +1));
    console.log($scope.var1);

}while($scope.var1<100)

$scope.var1 always stays 0, hence it goes to an infinite loop;