# Euler problems/51 to 60

### From HaskellWiki

## Contents |

## 1 Problem 51

Find the smallest prime which, by changing the same part of the number, can form eight different primes.

Solution:

problem_51 = undefined

## 2 Problem 52

Find the smallest positive integer, x, such that 2x, 3x, 4x, 5x, and 6x, contain the same digits in some order.

Solution:

problem_52 = undefined

## 3 Problem 53

How many values of C(n,r), for 1 ≤ n ≤ 100, exceed one-million?

Solution:

problem_53 = undefined

## 4 Problem 54

How many hands did player one win in the game of poker?

Solution:

problem_54 = undefined

## 5 Problem 55

How many Lychrel numbers are there below ten-thousand?

Solution:

problem_55 = length $ filter isLychrel [1..9999] where isLychrel n = all notPalindrome (take 50 (tail (iterate revadd n))) notPalindrome s = (show s) /= reverse (show s) revadd n = n + rev n where rev n = read (reverse (show n))

## 6 Problem 56

Considering natural numbers of the form, ab, finding the maximum digital sum.

Solution:

problem_56 = undefined

## 7 Problem 57

Investigate the expansion of the continued fraction for the square root of two.

Solution:

problem_57 = undefined

## 8 Problem 58

Investigate the number of primes that lie on the diagonals of the spiral grid.

Solution:

problem_58 = undefined

## 9 Problem 59

Using a brute force attack, can you decrypt the cipher using XOR encryption?

Solution:

problem_59 = undefined

## 10 Problem 60

Find a set of five primes for which any two primes concatenate to produce another prime.

Solution:

problem_60 = undefined