Learning is Interactive

jQuizMe 2.1 Release Page

This holiday break gave me the time that I need to push out a next release of jQuizMe.
Check it out at Google Code, jQuizMe.

Please leave your feedback in the comment box.

What are Sig Figs? Tutorial

By the end of this tutorial you will understand:

• What sig figs are.
• The fastest way to find to the sig figs.
• How to place your answer in sig figs after arithmetic.

What are sig figs?

Simply put, sig figs is the degree of reliability for a measurement. Calculations done on a measurement are as accurate as the least reliable measurement. You will encounter sig figs in chemistry, when dealing with atomic structures, and molecular. It’s worth noting that Sig Figs are commonly called Significant Figures, or Significant Digits. But I prefer Sig Figs.

The fastest way to finding sig figs.

The traditional way of teaching sig figs contains too many conditions. List of rules here. So, I found a way to simplify the approach into the following statement.

Sig figs are the number of digits from the “first nonzero” to the “last position”.
The “Last Position” is the last number’s position if the measurement has a decimal. Otherwise, the “Last Position” is the last non-zero’s position.
The “First NonZero” is the position of the first non-zero.

Another way of writing this is below.
Number of sig figs = ( “Last Position” – “First NonZero” ) + 1
NOTE: If the measurement is defined, then all the numbers are sig figs.

Now let’s do a few examples.
Note that “method 1″ is done by counting. While method 2 is done by using the algorithm.

Question 1: 1200 has how many sig figs?
Answer: 2 sig figs.
Method 1: The first is 1, and the last is 2. There are two digts from digit 1 to digit 2. Therefore 2 sig figs.
Method 2: ( “Last Position” – “First NonZero” ) + 1 ) = (2 – 1) + 1 = 1 + 1 = 2 sig figs

Question 2: 1200.25 has how many sig figs?
Answer: 6 sig figs
Method 1: The first is digit 1 and the last is digit 5 because there is a decimal. There are 6 digits from 1 to 5. Therefore 6 sig figs.
Method 2: ( “Last Position” – “First NonZero” ) + 1 ) = (6 – 1) + 1 = 5 + 1 = 6 sig figs

Question 3: 0.0025 has how many sig figs?
Answer: 2 sig figs
Method 1: The first is digit 2 and the last is digit 5. There are 2 digits from 2-5. Therefore 2 sig figs.
Method 2: ( “Last Position” – “First NonZero” ) + 1 ) = (5 – 4) + 1 = 1 + 1 = 2 sig figs

Question 4: 1.0010 has how many sig figs?
Answer: 5 sig figs.

Operations then sig figs:

When multiplying and dividing measurements, the result must have the same sig figs as the term with the least. However, you should ignore sig figs for unitless numbers.
When adding and subtracting, the result must have the same number of decimal places as the term with the least.

Example:
Question 5: What is the average of 130 in and 122.14 in
Answer: 76 in
Average is sum of the terms divided by 2.
130 in + 122.14 in = 152.14, only worry about sig figs after your calculation are done.
152 in / 2 = 76 in. 2 is unit-less, so you should consider sig figs in this operation.

Question 6: What is the 8,000 ft / 20 ft
Answer: 4 x 10³
8,000 ft / 20 ft = 4 x 10³. Not 400 because you must use the sig figs from the term with the least.

That concludes this tutorial.
Like always I appreciate feedback.

Javascript Tip: Convert string to unicode values

The following script will convert a string to the unicode values using javascript.
toUnicode is a extension to String.charCodeAt. The benefit of this function is that it returns the whole string a html unicode format.

String.prototype.toUnicode = function() {
var uni = [],
i = this.length;
while (i--) {
uni[i] = this.charCodeAt(i);
}
return "&#" + uni.join( ';&#' ) + ";";
};


Usage: obj.toUnicode();

Example: “<li/>”.toUnicode() //outputs: &#60;&#108;&#105;&#47;&#62;

DEMO

Here’s another method that I thought of.
This one is using a regexp instead of a while loop and an array to form the unicode text.

String.prototype.toUnicode = function () {
return this.replace(/./g, function (char) {
return "&#" + String.charCodeAt(char) + ";";
});
};

However, if possible use document.createTextNode to insert text instead of converting it to unicode. Document.createTextNode is a native DOM method meaning it’s a lot faster, and easier to understand .
More infor here: document.createTextNode

The Key to Success

A basic guide to success.
The key to success is hard work, healthy body and mind, network of support and an education.
Before you start, you must have a goal in life. This is what you will be working towards.

• Hard Work: Maintaining self confidence and motivation is the first start. Next planning and being proactive will help you towards achieving your goals.
  
  Top 10 Motivation Tips to Achieve your Goals
• A Healthy Body and Mind: What goes in, is what goes out. Thinking positive, eating right, and exercising, will increase your energy, performance and brighten up your days ahead.
  
  Self- Esteem & Confidence:
  How To Have A Healthy Body And Mind
• A Network of Support: The people you know is a main factor of success. You take on your surroundings, mainly your environment and your social network. If you want success, avoid negative surroundings. And join positive ones with people who have already achieved your goal.
  How to Network
• Education: Knowledge is power. Don’t do something without first understanding it. Therefore do research before starting a project.

With these simple tips, you can change your life and achieve your goals.