Multiplication sign facts for kids

The multiplication sign

The multiplication sign, also known as the times sign, is the symbol ×. It looks a bit like the lowercase letter "x". However, it's actually a special symbol that is the same even if you turn it upside down or sideways. We use it mostly in math, but it pops up in other places too!

What the Multiplication Sign Means

In math, the symbol × has several important uses:

Multiplying Numbers

• When you see two regular numbers with a × between them, it means you should multiply them.
• For example, in "2 × 3", you would read it as "2 times 3" or "2 multiplied by 3". The answer is 6.

Describing Sizes

• The × sign can also describe the size or dimensions of something.
• If a room is "10 feet × 12 feet", it means the room is 10 feet long and 12 feet wide. You would read this as "10 feet by 12 feet".
• It's also used to describe the size of a matrix, which is like a grid of numbers.

Special Math Uses

• In more advanced math, the × sign can mean different things.
• For vectors (which are like arrows with direction and length), it can mean a "cross product". This is a special way to multiply vectors.
• For sets (collections of items), it can mean a "Cartesian product". This creates new pairs from items in two different sets.

In Biology

• In the world of plants, the multiplication sign is used for "hybrid" names.
• A hybrid plant is a mix of two different types of plants.
• For example, Crocosmia × crocosmiiflora means this plant is a hybrid that came from two other Crocosmia species.
• Sometimes, people just use a regular "x" if the special × symbol isn't available.

For Dates

• Historians sometimes use the × sign between two dates.
• For example, "1225×1232" means an event happened sometime between the year 1225 and the year 1232. It tells you the earliest and latest possible times.

History of the Sign

The multiplication sign (×) was first used in a book around 1618. It was introduced by a mathematician named William Oughtred. However, similar symbols might have been used even earlier, in the mid-1500s.

Other Ways to Show Multiplication

Sometimes, you might see other ways to show multiplication:

The Letter "x"

• The letter "x" is sometimes used instead of the multiplication sign.
• However, in proper math writing, it's usually best to use the actual × symbol. This helps avoid confusion with the letter "x" when it's used as a variable.

Hidden Multiplication

• In algebra (a type of math that uses letters and symbols), the multiplication symbol is often left out.
• For example, "a multiplied by b" can just be written as "ab". This means "a times b".

Other Symbols

• On computer keyboards, you often see the asterisk (*) used for multiplication.
• This is common in computer programming and on calculators.
• It helps avoid confusion with the letter "x" when you are typing.