PHP 在字符串文字中动态引用变量

我有多个PHP变量，形式如下

$number1, $number2, $number3 and so on...

我想在循环中动态引用这些变量以从中检索信息，但不确定如何动态引用静态变量。前任：

for($i = 1; $i <= 10; $i++) {
    //The first number to be printed should be the value from
    //$number1 not $number concatenated to $i
    //here are some of the strings I tried:
    echo "$number$i";
    echo "{$number}$i";
    echo "{$number}{$i}";
}