We know that 10 drops of liquid is .1 fluid ounces. What we could do is divide 0.1 by 10 to find what 1 drop of liquid is, 0.1 divided by 10 is equal to 0.01 fluid ounces.
What we can then do knowing what 1 fluid ounce is, is multiply it by 1000.
0.01 * 1000 = 10
The volume of 1000 drops is 10