# Euler problems/51 to 60

(Difference between revisions)

## 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 = undefined`

## 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`