**"Number patterns"**

## Sandwich Puzzle

*By toni On 24 November, 2021 · Leave a Comment*

Suppose you have two 1s, two 2s and two 3s.

Arrange these six digits in a list so that:

between the two 1s there is one digit giving 1?1,

between the two 2s there are two digits giving 2??2,

between the two 3s there are three digits giving 3???3.

[…]

## Farey Sequences

*By toni On 23 November, 2021 · Leave a Comment*

It is not difficult to put a list of decimals in order of size. But what about ordering fractions?

John Farey introduced sequences of sequences of fractions in order of size, now called Farey sequences. Can you discover his method from the following examples?

## Magic Numbers

*By toni On 6 October, 2021 · Leave a Comment*

What patterns do you see in them?

Suppose you have to share 9872 gold coins between 8 people.

You give the coins out in thousands until there are less than 8000 left.

Then you give out one hundred at a time until there are less than 800, then […]

## Money Bags

*By toni On 1 September, 2021 · 2 Comments*

Ram had 15 coins, all the same kind, and he put them into 4 bags.

He labelled each bag with the number of coins inside it.

He could then pay any sum of money from 1 coin to 15 coins using one or more of the bags without opening any of the bags.

How […]

1. What do you see in this picture?

Give a proof linked to this picture of the formula $a^2 – b^2 = (a + b)(a – b)$ .

2. What do you notice about the difference between squares of consecutive numbers?

Compare the differences between squares of numbers that differ by 1 […]

## Triangle Number Picture

*By toni On 5 February, 2021 · Leave a Comment*

Is a picture worth a thousand words, as the saying goes?

This picture shows the first 4 triangle numbers: 1, 3, 6 and 10 and how you can fit 2 identical copies of a triangle together to form a rectangle.

Can you use it to find the number of dots in the […]

## Blocks, Bricks and Boxes

*By toni On 5 February, 2021 · Leave a Comment*

Find a cuboid (with edges of integer values) that has a surface area of exactly 100 square units.

Is there more than one?

It is quite easy to find a few solutions. The big challenge is to find all possible solutions.

Can you provide a convincing argument that you have found […]

## Magic of 37

*By toni On 1 February, 2021 · Leave a Comment*

First complete the number sentences by putting = + – x or ÷ in the boxes. Then explain why the pattern occurs.

Explore the pattern you get when you carry on these multiplications up to 37 × 54.

Click here for MAGIC OF 37 worksheet.

Click here for the Notes […]

## Mystic Rose

*By toni On 31 January, 2021 · Leave a Comment*

What can you see in this diagram?

Could you draw it? Could you draw a similar diagram with just 5 or 6 points around the outside? Try it?

How many lines are there in your diagrams? How many lines are there in the original diagram? Can you find a way of working out […]

## Prime Sieve

*By toni On 7 January, 2021 · Leave a Comment*

You might like to start by investigating the patterns you get when you shade multiples of a number on a grid. Download here

For the prime sieve investigation use a 100 square grid (download here):

Circle the number 2. Put a line through every multiple of 2 up to 100.

[…]

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