Task: What is the greatest product of four adjacent numbers in the same direction - up, down, left, right, or diagonally - in the 20x20 grid?

Task: What is the value of the first triangle number to have over five hundred divisors?

Task: Work out the first ten digits of the sum of the given one-hundred 50-digit number.

Task: Which number under one million produces the longest chain?

Task: How many lattice routes are there through a 20×20 grid?

Task: What is the sum of the digits of the number 2^1000?

Task: If all the numbers from 1 to 1000 (one thousand) inclusive were written out in words, how many letters would be used?

Task: Find the maximum total from top to bottom of the triangle below.

Task: How many Sundays fell on the first of the month during the twentieth century (1 Jan 1901 to 31 Dec 2000)?

Task: Find the sum of the digits in the number 100!