Tech Tutorials

Math can be terrifying for many people. This list will hopefully improve your general knowledge of mathematical tricks and your speed when you need to do math in your head.

1. Multiplying by 9, or 99, or 999

Multiplying by 9 is really multiplying by 10-1.

So, 9×9 is just 9x(10-1) which is 9×10-9 which is 90-9 or 81.

Let’s try a harder example: 46×9 = 46×10-46 = 460-46 = 414.

One more example: 68×9 = 680-68 = 612.

To multiply by 99, you multiply by 100-1.

So, 46×99 = 46x(100-1) = 4600-46 = 4554.

Multiplying by 999 is similar to multiplying by 9 and by 99.

38×999 = 38x(1000-1) = 38000-38 = 37962.

2. Multiplying by 11

To multiply a number by 11 you add pairs of numbers next to each other, except for the numbers on the edges.

Let me illustrate:

To multiply 436 by 11 go from right to left.

First write down the 6 then add 6 to its neighbor on the left, 3, to get 9.

Write down 9 to the left of 6.

Then add 4 to 3 to get 7. Write down 7.
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Your laptop battery has a finite amount of energy. By changing a few of your habits and configs on your laptop you can easily increase how long your battery will last per charge.
Depending upon the model, a notebook battery usually lasts from 1 to 8 hours. However, with efficient battery usage, an hour or two of battery power can significantly be increased. You can save battery power by using the built-in battery saving modes and by following good notebook battery-saving practices.
Built-in battery-saving modes are Stand By and Hibernate. In the Stand By mode, open applications are stored in the RAM, the hard disks power down, the monitor switches off, but the processor goes on running. When you again perform some activity of the mouse or the keyboard, then the hard disk powers up, the monitor switches on, and the data from the RAM is activated, restoring your notebook exactly the way you left it.Read more..

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Hot on the trail of Wii Fit is another device that measures your balance (far more precisely than the video game's balance board, one would hope).
In development by MIT researchers, the iShoe is an insole containing a sensor that measures a foot's pressure distribution. The sensor sends the data to a computer, which analyzes the information with a special algorithm. The hope is that this technology will allow doctors to detect balance problems in patients before it's too late to take the necessary steps to fix them.
Let's hope these researchers run -- not walk -- with developing this technology to bring it to doctors as soon as possible.

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Here are a few handy tips to clean your priceless collection of CDs and DVD discs.
But before you try any of these methods, remember that the disc media is very delicate and you may unintentionally damage the shiny reflective surface if you are not careful:
 » If dust particles are sticking to the CD surface, use a piece of soft cloth to wipe off the dust. To hold the CD, insert a finger or thumb inside the center hole of the CD or handle it by the edges but never touch the shiny surface.
 » If the DVD surface feels sticky or greasy, mix some baby shampoo in lukewarm water and use cotton or soft cloth to gently rub the CD surface with this solution. Make sure the CD is completely dry (no water drops) before putting it back in the jewel case.
 » If there are fingerprint marks on the CD surface, dip a soft cloth in Isopropyl Alcohol/Ethanol/Methanol and gently wipe the surface. Never use a petroleum based solvent like Acetone as that will permanently damage the CD surface.Read more..

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