从数字中删除前导/尾随数字的最佳方法是什么？

If I have a number like 12345, and I want an output of 2345, is there a mathematical algorithm that does this? The hack in me wants to convert the number to a string, and substring it. I know this will work, but I'm sure there has to be a better way, and Google is failing me.If I have a number like 12345, and I want an ou