# import necessary libraries
import pandas as pd
import numpy as np

# create a dataframe
df = pd.DataFrame({'A': [1, 2, 3], 'B': [4, 5, 6], \
                    'C': [7, 8, 9], 'D': [10, 11, 12]})

# find row, col number of value 6 in B column
row, col = np.nonzero(df.values == 6)

# print the results
print('Row:', row[0])
print('Column:', col[0])