Working systematically

Jack has nine tiles. He put them together to make a square so that two tiles of the same colour were not beside each other. Can you find another way to do it?

What do the digits in the number fifteen add up to? How many other numbers have digits with the same total but no zeros?

My cousin was 24 years old on Friday April 5th in 1974. On what day of the week was she born?

Exactly 195 digits have been used to number the pages in a book. How many pages does the book have?

There are 44 people coming to a dinner party. There are 15 square tables that seat 4 people. Find a way to seat the 44 people using all 15 tables, with no empty places.

This magic square has operations written in it, to make it into a maze. Start wherever you like, go through every cell and go out a total of 15!

How many triangles can you make using sticks that are 3cm, 4cm and 5cm long?

Can you find the value of t in these equations?

Can you swap the black knights with the white knights in the minimum number of moves?

You have twelve weights, one of which is different from the rest. Using just 3 weighings, can you identify which weight is the odd one out, and whether it is heavier or lighter than the rest?