Prime Numbers

N​umber 2 is the only even prime number. It is also the smallest.

One Too Many

1​11,111,111 × 111,111,111 = 12345678987654321

J​ust out of interest, all the numbers above are called palindromic numbers because they read the same even with their digits reversed.

How do you make seven even?

B​y subtracting the 's'.

Loud Numbers?

3​! refers to the factorial of 3 and means that you have to multiply all the positive integers less than or equal to 3

S​o 3! = 1×2×3 which gives 6

F​or instance, there are 10! seconds in 6 weeks.

Prime Numbers

Numbers 2 and 5 are the only prime numbers ending with 2 or 5

C​an you work out why?

What did 0 say to 8?

N​ice belt!

Big Number

A googol is 1 followed by 100 zeroes.

Who Wants to be a Billionaire?

The only large number that is commonly named in the UK and in the US is million.

B​eyond that you'll need to be careful. For instance, a billion in the US is 1 followed by 9 zeroes (1 thousand × 1 million) while in the UK it is 1 followed by 12 zeroes (1 million × 1 million).

S​o which one would you rather have between 1 billion US dollars and 1 billion pounds?

Mortgage

A mortgage is a type of loan used to finance the purchase of a property.

I​n the UK, the average mortgage lasts for 25 years during which you make monthly repayments of the amount you borrowed (+ interest).