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There are 22 NRICH Mathematical resources connected to Algorithms, you may find related items under Decision Mathematics and Combinatorics.

Broad Topics > Decision Mathematics and Combinatorics > Algorithms

### Probably a Code?

##### Age 16 to 18 Challenge Level:

Is the regularity shown in this encoded message noise or structure?

### Sorted

##### Age 14 to 18 Challenge Level:

How can you quickly sort a suit of cards in order from Ace to King?

### Ip?

##### Age 16 to 18 Challenge Level:

Seventh challenge cipher

### Jluuis or Even Asutguus?

##### Age 16 to 18 Challenge Level:

Sixth challenge cipher

### Up a Semitone?

##### Age 16 to 18 Challenge Level:

Fifth challenge cipher

### Semicircle

##### Age 16 to 18 Challenge Level:

Fourth challenge cipher

### Vital?

##### Age 16 to 18 Challenge Level:

Third challenge cipher

### A Fine Thing?

##### Age 16 to 18 Challenge Level:

Second challenge cipher

### Stage 5 Cipher Challenge

##### Age 16 to 18 Challenge Level:

Can you crack these very difficult challenge ciphers? How might you systematise the cracking of unknown ciphers?

### The Best Square

##### Age 14 to 18 Challenge Level:

How would you judge a competition to draw a freehand square?

### Happy Birthday

##### Age 16 to 18 Challenge Level:

Can you interpret this algorithm to determine the day on which you were born?

### An Introduction to Computer Programming and Mathematics

##### Age 16 to 18

This article explains the concepts involved in scientific mathematical computing. It will be very useful and interesting to anyone interested in computer programming or mathematics.

### Peaches in General

##### Age 14 to 16 Challenge Level:

It's like 'Peaches Today, Peaches Tomorrow' but interestingly generalized.

### Zeller's Birthday

##### Age 14 to 16 Challenge Level:

What day of the week were you born on? Do you know? Here's a way to find out.

### Unusual Long Division - Square Roots Before Calculators

##### Age 14 to 16 Challenge Level:

However did we manage before calculators? Is there an efficient way to do a square root if you have to do the work yourself?

### Procedure Solver

##### Age 16 to 18 Challenge Level:

Can you think like a computer and work out what this flow diagram does?

### Stretching Fractions

##### Age 14 to 16 Challenge Level:

Imagine a strip with a mark somewhere along it. Fold it in the middle so that the bottom reaches back to the top. Stetch it out to match the original length. Now where's the mark?

### Tournament Scheduling

##### Age 11 to 16

Scheduling games is a little more challenging than one might desire. Here are some tournament formats that sport schedulers use.

### Divided Differences

##### Age 16 to 18

When in 1821 Charles Babbage invented the `Difference Engine' it was intended to take over the work of making mathematical tables by the techniques described in this article.

### Vedic Sutra - All from 9 and Last from 10

##### Age 14 to 16 Challenge Level:

Vedic Sutra is one of many ancient Indian sutras which involves a cross subtraction method. Can you give a good explanation of WHY it works?

### Triangle Incircle Iteration

##### Age 14 to 16 Challenge Level:

Keep constructing triangles in the incircle of the previous triangle. What happens?

### Route to Root

##### Age 16 to 18 Challenge Level:

A sequence of numbers x1, x2, x3, ... starts with x1 = 2, and, if you know any term xn, you can find the next term xn+1 using the formula: xn+1 = (xn + 3/xn)/2 . Calculate the first six terms of this. . . .