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2009-09-21 15:46

Work out the first ten digits of the sum of the following one-hundred 50-digit numbers.

37107287533902102798797998220837590246510135740250
46376937677490009712648124896970078050417018260538
74324986199524741059474233309513058123726617309629
91942213363574161572522430563301811072406154908250
23067588207539346171171980310421047513778063246676

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Project Euler Problems NO：12

2009-09-21 14:58

The sequence of triangle numbers is generated by adding the natural numbers. So the 7^th triangle number would be 1 + 2 + 3 + 4 + 5 + 6 + 7 = 28. The first ten terms would be:

1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...

Let us list the factors of the first seven triangle numbers:

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Project Euler Problems NO：11

2009-09-21 12:25

In the 2020 grid below, four numbers along a diagonal line have been marked in red.

08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79

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Project Euler Problems NO：10

2009-09-21 11:13

The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.

Find the sum of all the primes below two million.

题意：200W一下质数的和

解题：还是质数还是用上次用到的质数判断的方法计算出200W一下的和

程序就不写了题目大同小异，答案是142913828922

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Project Euler Problems NO：9

2009-09-21 11:11

A Pythagorean triplet is a set of three natural numbers, a b c, for which,

a² +

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Project Euler Problems NO：8

2009-09-21 10:56

Find the greatest product of five consecutive digits in the 1000-digit number.

73167176531330624919225119674426574742355349194934
96983520312774506326239578318016984801869478851843
85861560789112949495459501737958331952853208805511
12540698747158523863050715693290963295227443043557
66896648950445244523161731856403098711121722383113
62229893423380308135336276614282806444486645238749
3035890729629049156044077239071

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Project Euler Problems NO：7

2009-09-21 10:45

By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6^th prime is 13.

What is the 10001^st prime number?

题意：第10001个质数

解题：原理和之前质数的一样从6N+/-1入手可以快速算出答案

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Project Euler Problems NO：6

2009-09-21 10:32