Evaluating Expressions for Kids: Put a Number in for x (Grade 6 Math)

Hi, I'm Luna from DoodleBeez. Today we are learning about expressions. An expression is a math phrase with numbers and letters. The letter is called a variable. It stands for a number we can change.

When a number sits right next to a letter, we multiply. Three x means three times x. If x is four, then three x is three times four, which is twelve.

To evaluate an expression, put the number in where the letter is. Let's find two x plus five when x is three. Two times three is six. Six plus five is eleven.

Remember the order of operations. Multiply before you add or take away. Let's find four x minus seven when x is six. Four times six is twenty four. Twenty four minus seven is seventeen.

A small two above the letter means squared. X squared means x times x. If x is five, x squared plus two is five times five, which is twenty five, plus two. That makes twenty seven.

Expressions help in real life. A game costs eight dollars per player plus a three dollar fee. The cost is eight p plus three. For four players, that is thirty two plus three, which is thirty five dollars.

Now it's your turn. What is three x plus four when x is seven? Pause and try. Three times seven is twenty one. Twenty one plus four is twenty five.

Great job! Remember, a variable is a letter that stands for a number. Put the number in for the letter, then multiply before you add or take away. Practice expressions in Middle School Math at doodlebeez.com. See you next time!