What is the shortest way to invest money? Like making double of capital $100,000 within shortest period?

If by short you mean 2 to 4 years try investing in life settlements or viatical settlements. These investments can get very high returns from typically about 16% to 22% and sometimes higher,and with little to NO risk to your priciple if you find the right companies. Be weary though, there are a bunch of crap companies out there that will just rip you off, but I have had personal experiance with a couple of top notch companies and have seen it happen. I guarantee that a majority of the folks on here have never even heard of these investments, but there is an alternative to the stock market and mutual funds. You just have to know where to look.

good luck

winning the lottery

Something high risk, like lottery tickets.

Invest in Real Estate.

The rate of return on an investment usually reflects it's risk. If you invest in a penny stock you could triple your money in a day. However you could also lose everything. Zero risk investments (if they existed) would reflect the 10 year US T-Bill rate of return.

Best way to do it is to know more about your investment opportunity than other investors, that way you can get the risk premium w/o taking the full risk.

Like anything else in investing, it depends on what chance you are willing to take that you will loose all or part of your investment.

You could double your investment quickly in the commodity futures market, but there is also a good chance that you will lose it all, too.

Junk bonds pay a higher rate of return than treasury bonds because there is a greater risk of loosing your money.

If you don't care about whether or not you lose your money, then just go to a casino roulette table, put it all on red or black for one spin. The chances are
18/38 that you will will double your money in a mater of seconds.

Disclaimer: Most financial advisors would not view any activity where you are trying to double your money in the shortest amount of time as "investing".
They would call it speculating or gambling because that's what it is.

If you want to double your money in a very short time, The best way is to bet "Black" on the roulette table. or Red....

If you really learn the stock market, especially Fundamental Analysis (company financials) and Technical Analysis (investor sentiment) you may learn how to invest wisely and avoid loss. Many use "stop loss" orders to prevent a serious loss when a stock goes down and also use a trailing stop loss to keep most of their profits if a stock goes up. Use a Roth IRA at the maximum savings rate to accumulat a nest egg. After you use other money (that you can afford to lose) to learn the ropes using a discount stock broker (such as Scott Trade) to make trades at about $7 commission per trade, you can trade using Roth IRA funds (that you can't afford to lose) to save on taxes and compound your earnings. If you gain say 10% a month, your investment can gain rapidly. Try this: Take $10,000 and multiply it by 1.1 over and over and see how many times it takes to reach a million dollars. How long do you have to invest, how many months? Now try that again multiplying by 2.0 (if you can select stocks that double). See the source for what you will have to learn.

Remember there are no guarantees. It has been said that the easiest way to become a millionaire ... is to start with three million. Good luck.