Problem 63 Powerful digit counts
Problem 63: Powerful digit counts
The 5-digit number, 16807=75, is also a fifth power. Similarly, the 9-digit nu[……]
The 5-digit number, 16807=75, is also a fifth power. Similarly, the 9-digit nu[……]
The cube, 41063625 (3453), can be permuted to produce two other cubes: 56623104 ([……]
Triangle, square, pentagonal, hexagonal, heptagonal, and octagonal numbers[……]
The primes 3, 7, 109, and 673, are quite remarkable. By taking any two primes and co[……]
Each character on a computer is assigned a unique code and the preferred standard is[……]
Starting with 1 and spiralling anticlockwise in the following way, a square spiral wit[……]
每次扩展,相当于将 1/2 替换为 1/(2+1/2),所以
第 1 次扩展结果: fraction = 1 + 1/2
第 2 次扩展结果:[......]
A googol (10100) is a massive number: one followed by one-hundred zeros; 100100 i[……]
If we take 47, reverse and add, 47 + 74 = 121, which is palindromic.
Not all numbers[……]
扑克游戏
扑克游戏中,一手牌包括5张卡牌,并且等级(rank)从低到高排序如下:
组合 C(n,r) 表示从 n 个数中选择 r 个数选择方案的总数。 当 1 ≤ n ≤ 1000时, 统计有多少个 C(n,r) 的值超过了[……]
It can be seen that the number, 125874, and its double, 251748, contain exactly t[……]
By replacing the 1st digit of the 2-digit number *3, it turns out that six[……]
The prime 41, can be written as the sum of six consecutive primes:
41 = 2 + 3[……]
Pentagonal numbers are generated by the formula, Pn=n(3n−1)/2. The first ten pentag[……]