Multiples of 9

If you add up the digits of any number in the 9 times table, you’ll always get 9.

e.g. 243 is in the 9 times table (it’s 27 × 9)

2 + 4 + 3 = 9

99 is in the 9 times table (it's 11 × 9)

9 + 9 = 18

Oh no! That's not 9...add up again

1 + 8 = 9

Infinity

The symbol for infinity is ∞

Where do mathematicians go to in New York?

Times Square

Natural Numbers

The positive numbers that we count with (1, 2, 3, 4, ...) have a special name.

They are called Natural numbers.

Mean

The mean is a type of average.

To calculate it, add all the numbers together and divide by how many there are.

Median

The median is a type of average.

To find it, put the numbers in order and find the middle.

Mode

The mode is a type of average.

It is the most common value, and is the only type of average that can be used with non-numerical data.

How do you count cattle?

With a cow-culator.

Pieces of Eight

You may have heard pirates in films say 'pieces of eight', but where does this come from?

The Spanish silver dollar at the time was worth 8 Reales (a unit of currency in Spain before 1868), and because, unlike today, cutting up or defacing money wasn't illegal, people would cut the dollar coin into 8 pieces to be used as change when trading!