Starting with 1 and spiralling anticlockwise in the following way, a square spiral with side length 7 is formed.
37 36 35 34 33 32 31
38 17 16 15 14 13 30
39 18 5 4 3 12 29
40 19 6 1 2 11 ...
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其他好文 时间：
2015-07-08 22:37:59
阅读次数：
218
A googol (10100) is a massive number: one followed by one-hundred zeros; 100100 is almost unimaginably large: one followed by two-hundred zeros. Despite their
size, the sum of the digits in each num...
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其他好文 时间：
2015-07-08 09:39:56
阅读次数：
101
In the card game poker, a hand consists of five cards and are ranked, from lowest to highest, in the following way:
High Card: Highest value card.One Pair: Two cards of the same value.Two Pairs: Tw...
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其他好文 时间：
2015-07-07 17:09:16
阅读次数：
131
If we take 47, reverse and add, 47 + 74 = 121, which is palindromic.
Not all numbers produce palindromes so quickly. For example,
349 + 943 = 1292,
1292 + 2921 = 4213
4213 + 3124 = 7337
That is...
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其他好文 时间：
2015-07-07 16:56:48
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113
It can be seen that the number, 125874, and its double, 251748, contain exactly the same digits, but in a different order.
Find the smallest positive integer, x, such that 2x, 3x, 4x, 5x, and 6x, con...
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其他好文 时间：
2015-07-02 10:22:55
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165
The prime 41, can be written as the sum of six consecutive primes:
41 = 2 + 3 + 5 + 7 + 11 + 13
This is the longest sum of consecutive primes that adds to a prime below one-hundred.
The longest s...
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其他好文 时间：
2015-06-07 17:35:13
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129
The series, 11 + 22 + 33 + ... + 1010 = 10405071317.
Find the last ten digits of the series, 11 + 22 + 33 + ... + 10001000.
#include
#include
using namespace std;
string powe(int n)
{
stri...
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其他好文 时间：
2015-06-07 12:39:28
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128
It was proposed by Christian Goldbach that every odd composite number can be written as the sum of a prime and twice a square.
9 = 7 + 2×12
15 = 7 + 2×22
21 = 3 + 2×32
25 = 7 + 2×32
27 = 19 + 2...
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数据库 时间：
2015-06-07 11:12:04
阅读次数：
148
The first two consecutive numbers to have two distinct prime factors are:
14 = 2 × 7
15 = 3 × 5
The first three consecutive numbers to have three distinct prime factors are:
644 = 2² × 7 × 23
...
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其他好文 时间：
2015-06-07 11:08:41
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106
The nth term of the sequence of triangle numbers is given by, tn = ½n(n+1); so the first ten triangle numbers are:
1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
By converting each letter in a word to a...
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其他好文 时间：
2015-06-05 12:29:01
阅读次数：
128
