Mental calculations

Mathematicians are always looking for efficient methods for solving problems. How efficient can you be?

Can you work out which drink has the stronger flavour?

How many ways can you find to put in operation signs (+, −, ×, ÷) to make 100?

Charlie and Abi put a counter on 42. They wondered if they could visit all the other numbers on their 1-100 board, moving the counter using just these two operations: ×2 and -5. What do you think?

Here's a chance to work with large numbers...

Can you find ways to put numbers in the overlaps so the rings have equal totals?

In this twist on the well-known Countdown numbers game, use your knowledge of Powers and Roots to make a target.

Use the differences to find the solution to this Sudoku.