Add And Subtract Numbers

1. Excel Add Then Subtract

As you may recall, a mixed number consists of an integer and a proper fraction. Any mixed number can also be written as an improper fraction, in which the numerator is larger than the denominator, as shown in the following example: Example 1 To add mixed numbers, we first add the whole numbers together, and then the fractions. If the sum of the fractions is an improper fraction, then we change it to a mixed number. Here's an example.

Learn about and revise positive and negative numbers and how to add and subtract or multiply and divide them with BBC Bitesize KS3 Maths.

The whole numbers, 3 and 1, sum to 4. The fractions, 2/5 and 3/5, add up to 5/5, or 1. Add the 1 to 4 to get the answer, which is 5.

Example 2 If the denominators of the fractions are different, then first find equivalent fractions with a common denominator before adding. For example, let's add 4 1/3 to 3 2/5.

Using the techniques we've learned, you can find the least common denominator of 15. The answer is 7 11/15. Subtracting mixed numbers is very similar to adding them. But what happens when the fractional part of the number you are subtracting is larger than the fractional part of the number you are subtracting from? Here's an example: let's subtract 3 3/5 from 4 1/3.

First you find the LCD; here it's 15.

Adding positive numbers, such as 2 + 2, is easy. When we add a negative number to a positive number, or two negative numbers, that can sometimes seem tricky. However, there are some simple rules to follow and we introduce them here. Rule 1: Adding positive numbers to positive numbers—it’s just normal addition. For example: this is what you have learned all along.

3 + 2 are two positive numbers. You can calculate these problems the way you always have: 3 + 2 = 5. Rule 2: Adding positive numbers to negative numbers—count forward the amount you’re adding.

This is where it gets a little harder. Pay close attention to where the negative signs are placed in the problem. For example: -6 + 3.

This would reading “negative six plus three”. The best way to think about this problem is to use a number line that extends to the negative numbers. You’re starting with the negative number -6. And you’re adding three to that number, which means you are moving three spots to the right. The answer is -3. Rule 3: Adding negative numbers to positive numbers—count backwards, as if you were subtracting. Now, let’s look at the reverse equation.

When you are adding a negative number to a positive number you are effectively subtracting the second number from the first. For example, take 4 + (-2).

Excel Add Then Subtract

How does that look on the numbers line? You start at 4. And then you add the negative number, which means you are moving to the left – in the negative direction. Basically you are subtracting the 2. The answer is 2. 4 + (-2) = 2. Rule 4: Adding negative numbers to negative numbers— treat the problem like subtraction (counting backwards).

When you are adding a negative number to a negative number, it becomes subtraction, where you start from a negative point on the numbers line and move left. For example, -3 + (-2).

This reads “negative three plus negative 2”. You need to ignore the plus sign and recognize that the second negative means you are subtracting that number. We’re starting at -3. Then we subtract 2. The answer is -5.3 + (-2) = -5.