Multiplication and division

Cherri, Saxon, Mel and Paul are friends. They are all different ages. Can you find out the age of each friend using the information?

Look on the back of any modern book and you will find an ISBN code. Take this code and calculate this sum in the way shown. Can you see what the answers always have in common?

Work out Tom's number from the answers he gives his friend. He will only answer 'yes' or 'no'.

Where can you draw a line on a clock face so that the numbers on both sides have the same total?

What number could replace * so that */5 is between 3 and 4?

How far apart are the first and last bus stops in this bus route?

Two numbers can be placed adjacent if one of them divides the other. Using only $1,...,10$, can you write the longest such list?

Find the smallest whole number which, when mutiplied by 7, gives a product consisting entirely of ones.

Choose any four consecutive even numbers. Multiply the two middle numbers together. Multiply the first and last numbers. Now subtract your second answer from the first. Try it with your own numbers. Why is the answer always 8?

Try adding together the dates of all the days in one week. Now multiply the first date by 7 and add 21. Can you explain what happens?