1.25×103ppm1.25 \times 10^{3} \mathrm{ppm}1.25×103ppm
1.25×102ppm1.25 \times 10^{2} \mathrm{ppm}1.25×102ppm
1.25×10−3ppm1.25 \times 10^{-3} \mathrm{ppm}1.25×10−3ppm
1.25×10−2ppm1.25 \times 10^{-2} \mathrm{ppm}1.25×10−2ppm