Its not JUST about how long a song was number one. Yes Irreplaceable was #1 for 10 weeks, but lets remember that it TUMBLED down the charts as SOON as she stopped promoting it. The week after the promo train stopped for irreplaceable it tumbled out the top ten two weeks later and was out of the top 100 a month later. Party Rock Anthem was in the top ten for THIRTY WEEKS. It smashed from here to Mongolia. EVERYONE knows that song. No one checking for Irreplaceable like that. Same with We Found Love. We Found Love was a worldwide anthem that went #1 in 30 different countries. Only America used Single Ladies. Single Ladies only when number one in America and Brazil I think. And on top of that the radio airplay wasn't that impressive and the sales aren't groundbreaking neither. It was just a "popular" number one by BEYONCE. If any other artist sang it, it would've flopped because its not a particular memorable or iconic song. But Beyonce's video is the only iconic element of the single.