Een voorbeeld van een juiste berekening is:
(percentage verandering$=\frac{\text { nieuw - oud }}{\text { oud }} \times 100 \%
De huidige prijs is$100 \%+120 \%=220 \%van de nieuw prijs)\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ goedkoper}\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ goedkope}\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ goedkop}\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ goedko}\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ goedk}\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ goed}\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ goedk}\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ goedkp}\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ goedk}\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ goedk}\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ goed}\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ goe}\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ go}\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ g}\frac{100-220}{220}\times100\%=\frac{-120}{220}\times100\%=-54{,}5\%/54{,}5\%\text{ }$\frac{100-220}{220} \times 100 \%=\frac{-120}{220} \times 100 \%=-54{,}5 \% / 54{,}5 \%
