How many ng are there 5.27x10-13 kg

This involves metric conversion and one can easily use dimensional analysis, assuming you know the conversion factors.  

1 ng = 10-9 g, or put another way 109 ng = 1 g

1 kg = 103 g

5.27x10-13 kg x 1 g/1x10-3 kg x 1x109 ng/g = 5.27x10-1 ng = 0.527 ng

Looking at the individual steps and following the units, we have...

5.27x10-13 kg x 1 g/1x10-3 g = 5.27x10-10 g (kg cancel leaving g)

5.27x10-10 g x 1x109 ng/g = 5.27x10-1 ng = 0.527 ng (g cancel leaving ng)