Hallo "Anonymous",
15 % von 40 € = 15 % * 40 € = (15/100) * 40 € = 0,15 * 40 € = 15*40€/100= 6 €
Wie du das rechnen möchtest bleibt dir überlassen.
$${\mathtt{0.15}}{\mathtt{\,\times\,}}{\mathtt{40}} = {\mathtt{6}}$$
$${\frac{{\mathtt{15}}{\mathtt{\,\times\,}}{\mathtt{40}}}{{\mathtt{100}}}} = {\mathtt{6}}$$
$${\frac{{\mathtt{15}}{\mathtt{\,\times\,}}{\mathtt{4}}}{{\mathtt{10}}}} = {\mathtt{6}}$$
$${\frac{{\mathtt{3}}{\mathtt{\,\times\,}}{\mathtt{4}}}{{\mathtt{2}}}} = {\mathtt{6}}$$
Gruß radix !