A = 01, B = 02, C = 03, D = 04, E = 05, F = 06, G = 07, H = 08, I = 09, J = 10
K = 11, L = 12, M = 13, N = 14, O = 15, P = 16, Q = 17, R = 18, S = 19, T = 20
U = 21, V = 22, W = 23, X = 24, Y = 25, Z = 26

From Wikipedia

On April 29, 2011,[7] U.S. President Barack Obama authorized a raid on bin Laden's suspected location near Abbottabad, Pakistan. The operation was successfully carried out in the early morning of May 2 (due to weather and time considerations) by U.S. Navy SEALs with intelligence support from the Central Intelligence Agency (CIA).

...

The Arabic linguistic convention would be to refer to him as "Osama" or "Osama bin Laden", not "bin Laden" alone, as "bin Laden" is a patronymic, not a surname in the Western manner.

The Local Date in Pakistan at the time of the operation, 2011 5 2

Osama Bin Laden abbreviated as OBL.

O B L = 15 02 12, Rearranging all the numbers -> 2011 5 2