High-tech companies, investment banks and consulting firms are famous for their brainteasers. Anyone, after all, can come up with a canned answer to display their leadership and management skills - but fewer people can quickly come up with three solid reasons why a manhole cover is round. Whether you're applying for a technical, corporate finance or marketing position, expect to get a few of these beauties. Creativity and mental flexibility and speed are of paramount importance to high-tech firms, and one surefire way to test these qualities are through these slightly offbeat questions.

If you field one of these brainteasers, your interviewer may give you a time limit. Don't become flustered. Simply try to think through the question from every angle you can. Most questions require either logic, that ever-popular "out of the box" thinking, or both.

1. If you look at a clock and the time is 3:15, what is the angle between the hour and the minute hands?

The answer to this is not zero! The hour hand, remember, moves as well. The hour hand moves a quarter of the way between three and four, so it moves a quarter of a twelfth (1/48) of 360 degrees. So the answer is seven and a half degrees, to be exact.

2. A company has ten machines that produce gold coins. One of the machines is producing coins that are a gram light. How do you tell which machine is making the defective coins with only one weighing?

Think this through - clearly, every machine will have to produce a sample coin or coins, and you must weigh all these coins together. How can you somehow indicate which coins came from which machine? The best way to do it is to have every machine crank out its number in coins, so that machine 1 will make one coin, machine 2 will make two coins, and so on. Take all the coins, weigh them together, and consider their weight against the total theoretical weight. If you're four grams short, for example, you'll know that machine 4 is defective.

3. Four members of U2 (Bono, the Edge, Larry and Adam) need to get across a narrow bridge to play a concert. Since it’s dark, a flashlight is required to cross, but the band has only one flashlight, and only two people can cross the bridge at a time. (This is not to say, of course, that if one of the members of the band has crossed the bridge, he can’t come back by himself with the flashlight). Adam takes only a minute to get across, Larry takes two minutes, the Edge takes five minutes, and slowpoke Bono takes ten minutes. A pair can only go as fast as the slowest member. They have 17 minutes to get across. How should they do it?

The key to attacking this question is to understand that Bono and the Edge are major liabilities and must be grouped together. In other words, if you sent them across separately, you’d already be using fifteen minutes.

What does this mean? That Bono and the Edge must go across together. But they can not be the first pair (or one of them will have to transport the flashlight back). Instead, you send Larry and Adam over first, taking two minutes. Adam comes back, taking another minute, for a total of three minutes. Bono and the Edge then go over, taking ten minutes, and bringing the total to 13. Larry comes back, taking another two minutes, for a total of 15. Adam and Larry go back over, bringing the total time to 17 minutes.

4. What is the sum of the numbers from 1 to 50?

This is an relatively easy one: pair up the numbers into groups of 51 (1+50=51; 2+49 = 51; etc.). Twenty-five pairs of 51 equals 1275.