In Mathematica, looping is inefficient, It's better to do it all at once.
In[17]:= Table[{x, y, 2^x*5^y == 5000}, {x, 0, 5}, {y, 0, 5}]
Out[17]= {{{0, 0, False}, {0, 1, False}, {0, 2, False}, {0, 3,
False}, {0, 4, False}, {0, 5, False}}, {{1, 0, False}, {1, 1,
False}, {1, 2, False}, {1, 3, False}, {1, 4, False}, {1, 5,
False}}, {{2, 0, False}, {2, 1, False}, {2, 2, False}, {2, 3,
False}, {2, 4, False}, {2, 5, False}}, {{3, 0, False}, {3, 1,
False}, {3, 2, False}, {3, 3, False}, {3, 4, True}, {3, 5,
False}}, {{4, 0, False}, {4, 1, False}, {4, 2, False}, {4, 3,
False}, {4, 4, False}, {4, 5, False}}, {{5, 0, False}, {5, 1,
False}, {5, 2, False}, {5, 3, False}, {5, 4, False}, {5, 5,
False}}}
It also possible to select out the answer.
In[15]:= Select[Flatten [Table[{x, y}, {x, 0, 5}, {y, 0, 12}], 1],
2^#[[1]]*5^#[[2]] == 5000 &]
Out[15]= {{3, 4}}