- Topics At a Glance
- Different Types of Numbers
- Natural Numbers
- Whole Numbers
- Integers and Negative Numbers
- Integers and Absolute Value
- Rational Numbers
- Irrational Numbers
- Real Numbers and Imaginary Numbers
- Different Ways to Represent Numbers
- Fractions
- Equivalent Fractions
- Mixed Numbers
- Reducing Fractions
- Comparing Fractions
- Least Common Denominator
- Addition and Subtraction of Fractions
- Multiplication of Fractions
- Equivalent Fractions and Multiplication by 1
- Multiplication by Clever Form of 1
- Multiplicative Inverses
- Division of Fractions
- Multiplication and Division with Mixed Numbers
**Decimals**- Converting Fractions into Decimals
- Converting Decimals into Fractions
- Comparing Decimals
- Adding and Subtracting Decimals
- Multiplication and Division by Powers of 10
**Multiplying Decimals**- Dividing Decimals
- Infinite Decimals
- Percents
- Portion of the Whole
- Things to Do with Real Numbers
- Addition and Subtraction of Real Numbers
- Properties of Addition
- Subtraction
- Multiplication
- Division
- Long Division Remainder
- Exponents and Powers - Whole Numbers
- Properties of Exponents
- Prime Factorization
- Order of Operations
- Even and Odd Numbers
- Infinity
- Sequences
- is Irrational
- Counting Rational Numbers
- Counting Real Numbers?
- Counting Irrational Numbers
- In the Real World
- Decimals in Use
- How to Solve a Math Problem
- I Like Abstract Things: Summary

When multiplying a decimal number by another decimal number, it again helps to be reminded what they'd look like in fraction form.

**Sample Problem**

As with addition and subtraction, converting decimals to fractions and back again is pretty inefficient. Thankfully, just as with addition and subtraction, we can get around that. Just plow right through those "detour" signs.

In the example 0.8 x 0.4, we multiplied two decimals with one decimal place each. When we wrote the numbers as fractions, we were multiplying two fractions that each had 10 in the denominator. The product of those fractions gave us a denominator of 100, so the corresponding decimal had two decimal places. Once again, we're just counting zeros. Better than counting crows.

Suppose *a*, *b* and *c *are three decimal numbers. How do you figure out the number of decimal places in the product of *a* x *b *x *c*? (add the number of decimal places in *a* to the number of decimal places in *b *to the number of decimal places in *c*) Yes, unfortunately, you will need to know how to multiply three numbers together. Curse those three-dimensional shapes.

Example 1

Solve 0.06 x 0.2 |

Example 2

Solve 0.004 × 0.73 |

Exercise 1

Given 0.4 and 0.005, write each number as a fraction.

Exercise 2

Find the denominator of the product of and .

Exercise 3

How many decimal places will there be in the final product of 0.4 × 0.005?

Exercise 4

How many decimal places will there be in the product of 0.005 × 0.1237?

Exercise 5

How many decimal places will there be in the product of 0.3 × 0.87?

Exercise 6

Solve 0.03 x 0.15.

Exercise 7

Solve 0.2 x 0.001

Exercise 8

Solve 0.0005 x 0.0002.

Exercise 9

Solve 0.3 × 0.01 × 0.004

Exercise 10

Solve 0.245 x 0.02 x 0.9 x 0

Exercise 11

Solve 0.2 x 0.009 x 0.02