Arithmetic Grade Six

Lesson One Hundred Sixty-nine: Stock Value


You may be familiar with stock. If not, here's a real short explanation. Many companies sell shares of their company in the form of stock. Ordinary people are able to purchase these shares which makes them partial owners of a company. The value of shares of stock changes all the time and people can make money by buying and selling stock. 


	  Bob purchased 10 shares of stock in a company for $4 per 
	share. It is now worth $6 dollars per share. How much money
	did Bob make off this investment?
So, Bob bought 10 shares for $4 per share. That's $40 which Bob spent. The stock is now worth $6 per share. This means that he could sell the 10 shares of stock for $60. So, we can find how much he has made (and could lose) by subtracting the current price from the price he bought the stock for ($60 - $40 = $20). So, he's made $20 at this point (if he sells the stock).

Often we want to know how much the value of a stock has changed as a percent. Consider this problem:

Here's another example: 


	  A share of stock in Company A sold for $4 per share
	a week ago. It is now worth $5 per share. How much (as a
	percent) has the value of a share in Company A increased
	in the last week?
We can solve this problem in two steps:
  1. Find the amount of change in price: $5 - $4 = $1
  2. Divide the amount of change by the original price: $1 ÷ $4 = .25
We can represent this answer as 25% as a percent value.

Here are some more examples presented in a table: 


	ORIGINAL VALUE	CURRENT VALUE   INCREASE   	PERCENT INCREASE
	 $5 per share    $10 per share   $5 per share    100%
	 $2 per share	 $3 per share    $1 per share     50%
	$10 per share    $11 per share   $1 per share     10%
	$20 per share    $25 per share   $5 per share     25%

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