From the Ask Billboard column:
Hi Gary,
With "Glee: the Music, the Power of Madonna" at No. 1 on this week's Billboard 200 and her own Celebration album receiving a boost, re-entering at No. 86, it's gotten me thinking about Madonna's best-selling digital songs.
Could you please provide totals for her five best-selling tracks since 2005 (when digital sales began contributing to the Billboard Hot 100) and her 10 best-selling hits before then? That way, no newer tracks (i.e., 4 Minutes or Hung Up) that fans had the chance to purchase from the time of their release "unfairly" rank above older songs.
Also, what are Madonna's overall digital songs sales?
Thank you and keep up the good work,
Jim Radenhausen
Reeders, Pennsylvania

Hi Jim,
The spotlight on Madonna has certainly benefitted both "Glee" and the Queen of Pop. Make sure to check our Billboard cover story on the show, as well.
I, like millions of other viewers, thought that the "Glee" cast did a great job covering Madonna's catalog. Two personal favorite highlights from the April 20 episode: Lea Michele and Cory Monteith's walk-and-sing mash-up of Borderline and Open Your Heart - complete with Madonna look-alikes of various eras in the background - and Amber Riley's powerful solo on Like A Prayer.
As requested, here is a look at the digital sales to-date, according to Nielsen SoundScan through the week ending April 25, of Sue Sylvester's musical hero:

Top-Selling Madonna Titles Released Since 2005:
2,751,000, 4 Minutes
1,200,000, Hung Up
358,000, Sorry
316,000, Give It 2 Me
192,000, Celebration

Top-Selling Madonna Titles Released Before 2005:
443,000, Like A Prayer
322,000, Material Girl
311,000, Vogue
293,000, Ray Of Light
260,000, Holiday
240,000, Like A Virgin
217,000, Music
211,000, Crazy For You
189,000, Santa Baby
184,000, Die Another Day

Madonna has sold 11.6 million digital songs to date.