https://qiita.com/kft12/items/1ecec78a43b6b15570bf/revisions/3?type=preview
> (個人的に)良い例
> public int calculateTaxPrice(int price) {
> double tax = 1.1;
> return (int)(price * tax);
> }

お金の計算に浮動小数点演算使うのが良い例ってナンも分かってない感じ