Hallo!
1 % von 4000 = 4000 / 100 = 40
$${\mathtt{4\,000}}{\mathtt{\,\times\,}}{\mathtt{1}}\% = {\mathtt{40}}$$
7,5 % von 1234,45 = 7,5 * 1234,45 / 100 =925,90875
$${\mathtt{7.5}}\%{\mathtt{\,\times\,}}{\mathtt{12\,345.45}} = {\mathtt{925.908\: \!75}}$$
7.5 % von 1235,45 ist nicht 925,90875 sondern
noch einmal:
7,5 % = 7,5 / 100 = 0,075
0,075 * 1234,45 = 92,58375
$${\mathtt{0.075}}{\mathtt{\,\times\,}}{\mathtt{1\,234.45}} = {\mathtt{92.583\: \!75}}$$
Gru8 "radix"