Encyclopedia>Numbers and Quantities>Arithmetic>Addition and Subtraction>Addition with Help from the Number Line

Addition and plus are two names for the same mathematical operation. Adding positive numbers to each other makes things larger, and moves you towards the right on the number line.

Rule

When you are talking about addition, all the numbers you are adding together are called terms. When you add several terms together, the answer is called a sum.

$$\text{TERM}+\text{TERM}=\text{SUM}$$ |

It’s important to remember these names for different parts of an addition, so you should memorize them!

Example 1

**Evaulate **

$$3+6=9$$ |

In this case, 3 and 6 are the terms, and 9 is the sum.

Think About This

**What do you think will happen when you try to add 0 to another number? **

Absolutely nothing! Adding 0 to a term won’t change it.

$$10+0=10\phantom{\rule{1em}{0ex}}100+0=100\phantom{\rule{1em}{0ex}}42+0=42$$ |

This is because you are jumping 0 steps towards the right on the number line, so the number isn’t getting any larger.

Example 2

**Evaluate **

$$73+20=93$$ |

In this case, 73 and 20 are the terms, and 93 is the sum.

Remember that you can always use the number line to help you with addition. The number of jumps you need to jump to the right to get the answer is equal to the number you are adding.

Think About This

**What are some pairs of numbers that become 10 when you add them together? **

Some examples are: $$\begin{array}{llll}\hfill 1+9& =10\phantom{\rule{2em}{0ex}}& \hfill & \phantom{\rule{2em}{0ex}}\\ \hfill 8+2& =10\phantom{\rule{2em}{0ex}}& \hfill & \phantom{\rule{2em}{0ex}}\\ \hfill 3+7& =10\phantom{\rule{2em}{0ex}}& \hfill & \phantom{\rule{2em}{0ex}}\\ \hfill 6+4& =10\phantom{\rule{2em}{0ex}}& \hfill & \phantom{\rule{2em}{0ex}}\\ \hfill 5+5& =10\phantom{\rule{2em}{0ex}}& \hfill & \phantom{\rule{2em}{0ex}}\end{array}$$

Note that the order does not matter, both $1+9$ and $9+1$ equal 10.

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Subtraction with Help from the Number Line