Number operations & calculation methods

An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

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: x2 and -5. What do you think?

How many solutions can you find to this sum? Each of the different letters stands for a different number.

Can you find six numbers to go in the Daisy from which you can make all the numbers from 1 to a number bigger than 25?

Find the sum of this series of surds.

I'm thinking of a number. My number is both a multiple of 5 and a multiple of 6. What could my number be?

Which set of numbers that add to 100 have the largest product?

A cinema has 100 seats. Show how it is possible to sell exactly 100 tickets and take exactly £100 if the prices are £10 for adults, 50p for pensioners and 10p for children.

Can you arrange these numbers into 7 subsets, each of three numbers, so that when the numbers in each are added together, they make seven consecutive numbers?

Watch our videos of multiplication methods that you may not have met before. Can you make sense of them?

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

What is the smallest number of answers you need to reveal in order to work out the missing headers?

Can you crack these cryptarithms?

Just because a problem is impossible doesn't mean it's difficult...

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