sigma 10-22

Can anyone please tell me for sure if i need to or do not need to apply the 1.6 crop factor to this lens ? Sigma 10-20mm f4-5.6 EX DC HSM as it is specially made for a cropped body as someone has pointed out ? which would make it roughly 16-32mm by my maths on a Canon cropped body if i needed to...

Can anyone please tell me for sure if i need to apply the 1.6 crop factor to this lens as it is specially made for a cropped body as someone has pointed out ? which would make it roughly 16-32mm by my maths on a Canon cropped body?. Or not as its built specially for the ultra wide to be...