The sum of the squares of the first ten natural numbers is, 1^(2) + 2^(2) + ... + 10^(2) = 385 The square of the sum of the first ten natural numbers is, (1 + 2 + ... + 10)^(2) = 55^(2) = 3025 Hence the difference between the sum of the sq…

2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder. What is the smallest number that is evenly divisible by all of the numbers from 1 to 20? 単なる最小公倍数なのですぐにやり方はわかる…

A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99. Find the largest palindrome made from the product of two 3-digit numbers. 結構悩んだあげくに力技で解く．…

ここ数年，流行の行動経済学の新著．前著の『セイラー教授の〜』同様，内容は確かにおもしろいのだけど，結局は読み物でしかないのが残念．タイトルも英題のNudgeから実践行動経済学という明らかにビジネスな人たちを対象にしたタイトルになってしまっている…