
# 5: Decimals


Decimals are like fractions and represent non-whole number numbers.

• 5.1: Decimals
On 1/29/2001, the New York Stock exchange ended its 200-year tradition of quoting stock prices in fractions and switched to decimals. It was said that pricing stocks the same way other consumer items were priced would make it easier for investors to understand and compare stock prices. Supporters of the change claimed that trading volume, the number of shares of stock traded, would increase and improve efficiency. But switching to decimals would have another effect of narrowing the spread.
• 5.2: Introduction to Decimals
Recall that whole numbers are constructed by using digits.
• 5.3: Adding and Subtracting Decimals
Addition of decimal numbers is quite similar to addition of whole numbers. For example, suppose that we are asked to add 2.34 and 5.25. We could change these decimal numbers to mixed fractions and add.
• 5.4: Multiplying Decimals
Multiplying decimal numbers involves two steps: (1) multiplying the numbers as whole numbers, ignoring the decimal point, and (2) placing the decimal point in the correct position in the product or answer.
• 5.5: Dividing Decimals
In this and following sections we make use of the terms divisor, dividend, quotient, and remainder.
• 5.6: Fractions and Decimals
When converting a fraction to a decimal, only one of two things can happen. Either the process will terminate or the decimal representation will begin to repeat a pattern of digits. In each case, the procedure for changing a fraction to a decimal is the same.
• 5.7: Equations with Decimals
We can add or subtract the same decimal number from both sides of an equation without affecting the solution.
• 5.8: 5.7 Introduction to Square Roots
Once you’ve mastered the process of squaring a whole number, then you are ready for the inverse of the squaring process, taking the square root of a whole number.
• 5.9: The Pythagorean Theorem