Roman numerals

Hello, and welcome to Myriora Maths! What number is this? The Romans wrote numbers with letters, and we still see them today. Let's learn to read them!

Where do we see Roman numerals? On clock faces. In the names of kings and queens, like Henry the Eighth. And at the end of films, to show the year they were made.

Roman numerals use seven letters. The letter I is one. V is five. X is ten. L is fifty. C is one hundred. D is five hundred. And M is one thousand.

Usually, we just add the letters up. Two is two I's: one and one. Seven is V, I, I: five, one and one. Fifteen is X, V: ten and five. The big letters come first, then the smaller ones.

But four isn't four I's in a row. The Romans didn't like writing the same letter four times. So four is I, V: one before five, which means one less than five. And nine is I, X: one less than ten. When a small letter comes before a bigger one, take it away.

Let's try one together. What number is this: X, I, V? Look for a small letter before a bigger one. Say it out loud!

X is ten. Then I, V: one before five, which is four. Ten and four make fourteen. Well done if you said fourteen!

Now let's read the number from the start. M, M is two thousand. X, X is twenty. V, I is six. So it's two thousand and twenty-six: this year!

Here's a question that catches lots of people. What number is I, X? Some people say eleven, adding one and ten. But the small letter comes first! So it's one less than ten: nine.

Your turn! What number is X, X, I, X? Pick the right card. You've got fifteen seconds, or pause the video. Go!

Time's up! X, X is twenty. I, X is one less than ten: nine. Twenty and nine make twenty-nine!

Quick review. Learn the seven letters, from I for one to M for one thousand. Usually, add the letters up. And a small letter before a bigger one means take it away. See you next time!