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### How to Subtract Numbers

Subtraction is usually the second operation you discover, and it’s not much harder than addition. In fact, you can subtract larger numbers by stacking them in columns, similar to how you add large numbers [more…]

### How to Multiply Numbers

To multiply numbers, you need to know how to work with the different times signs as well as parentheses. If you multiply large numbers, you also need to know how to stack them in columns, so that you can [more…]

### How to Find the Least Common Multiple

The *least common multiple* (LCM) of a set of numbers is the lowest positive number that is a multiple of every number in that set. For example, the LCM of the numbers 2, 3, and 5 is 30 because [more…]

### How to Convert an Improper Fraction to a Mixed Number

Although improper fractions are great for solving math problems, the results may be easier for people to understand if you first convert them to mixed numbers. To convert an improper fraction to a mixed [more…]

### A Closer Look at Pi (p)

The symbol p (pi — pronounced *pie*) is a Greek letter that stands for the ratio of the circumference of a circle to its diameter. Here’s the approximate value of p: [more…]

### How to Subtract Fractions with the Same Denominator

Subtracting fractions with the same denominator (bottom number) is easy. When the denominators are the same, you can just think of the fractions as pieces of cake. [more…]

### Move the Decimal Point to Change a Number’s Value

When you’re working with whole numbers, you can multiply or divide any number by 10 just by moving the decimal point to the right or left, respectively. When you multiply by moving the decimal point to [more…]

### How to Round Decimals

Rounding decimals works almost exactly the same as rounding numbers. You will usually need to round a decimal either to a whole number or to one or two decimal places. [more…]

### How to Add Decimals

Adding decimals is almost as easy as adding whole numbers. As long as you set up the problem correctly, you’re in good shape. To add decimals, follow these steps: [more…]

### How to Subtract Decimals

Subtracting decimals is almost as easy as subtracting whole numbers. As long as you set up the problem correctly, you’re in good shape. Here’s how you subtract decimals: [more…]

### How to Multiply Decimals

Multiplying decimals is different from adding and subtracting them in that you don’t have to worry about lining up the decimal points. In fact, the only difference between multiplying whole numbers and [more…]

### How to Divide Decimals

When you know how to do long division, figuring out how to divide decimals is easy. However, unlike dividing whole numbers, with decimals, you have to add trailing zeros in the dividend and you also have [more…]

### How to Use Trailing Zeros and Leading Zeros in a Decimal Number

When you work with decimal numbers, you need to understand the difference between trailing zeros and leading zeros, as well as how they affect the value of the number. [more…]

### How to Convert between Percents and Decimals

It is easy to convert percents to decimals and decimals to percents. For example, to convert a percent to a decimal, you drop the percent sign (%) and move the decimal point two places to the left. That’s [more…]

### How to Convert from Percents to Fractions

Converting percents to fractions is fairly straightforward. Remember that the word *percent* means “out of 100.” So changing percents to fractions naturally involves the number 100. [more…]

### How to Split Up a Pizza into Unequal Amounts

You may have to add or subtract fractions in word problems that involve splitting up part of a whole into unequal amounts. For example, consider the following pizza problem: [more…]

### Calculate Addition and Subtraction Problems Using Decimals

You frequently work with decimals when dealing with money, metric measurements, and food sold by the pound. The following problem requires you to add and subtract decimals. Even though the decimals may [more…]

### Calculate Percentages Using Addition and Subtraction

Many real-life problems involve adding and subtracting percents. For example, percents can represent answers in polls, votes in an election, or portions of a budget, and the total often has to add up to [more…]

### Multiply Decimals and Percents in Word Problems

The word *of* in a word problem usually means multiplication. This idea is also true in word problems involving decimals and percents. The method for solving these two types of problems is similar, as you’ll [more…]

### How to Determine a Salary Increase Based on a Percentage

If you need to calculate someone’s *salary increase*or *raise* based on the percentage of the raise, you can do this using the distributive property. Here’s an example: [more…]

### How to Calculate Interest on Top of Interest

When you receive interest from the bank, you get more money. And when you earn interest on the interest you earned earlier, this makes the dollar amounts grow even faster. Here’s an example: [more…]

### How to Calculate a Percentage Discount

You can use subtraction to calculate a percentage discount. In fact, when you hear the words *discount* or *sale price*, you should automatically think of subtraction. Here’s an example: [more…]

### How to Simplify Numbers Using Scientific Notation

When working with extremely large or small numbers, you can save on time and space — and make calculations easier — by using scientific notation. As you will see, it uses both decimals and exponents to [more…]

### How to Estimate Metric Amounts

One reason people sometimes feel uncomfortable using the metric system is that when you’re not familiar with it, estimating amounts in practical terms is hard. For example, if your friend invites you to [more…]

### How to Determine Likelihoods Using Basic Probability

Probability is the mathematics of deciding how likely an event is to occur. It has a wide variety of applications in insurance, weather prediction, biological sciences, and even physics. For example, [more…]