Euler problems/11 to 20

Problem 11

What is the greatest product of four numbers on the same straight line in the 20 by 20 grid?

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Problem 12

What is the first triangle number to have over five-hundred divisors?

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Problem 13

Find the first ten digits of the sum of one-hundred 50-digit numbers.

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Problem 14

Find the longest sequence using a starting number under one million.

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Problem 15

Starting in the top left corner in a 20 by 20 grid, how many routes are there to the bottom right corner?

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Problem 16

What is the sum of the digits of the number 2¹⁰⁰⁰?

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Problem 17

How many letters would be needed to write all the numbers in words from 1 to 1000?

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Problem 18

Find the maximum sum travelling from the top of the triangle to the base.

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Problem 19

How many Sundays fell on the first of the month during the twentieth century?

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Problem 20

Find the sum of digits in 100!

Solution:

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