A calculation

How much work effort and storage space is needed to create such a bulky hoard of calories? Regarding work effort, given that freshly collected nectar is (on average) a 40 percent sugar solution and fully ripened honey is roughly an 80 percent sugar solution, and given that a foraging bee typically brings home a nectar load weighing about 40 milligrams (0.001 ounces), we can calculate that the collection of enough nectar to produce 20 kilograms (44 pounds) of honey requires more than 1 million foraging trips by a colony’s workers

In this text I’m wondering how 1 million trips can come out.

My calculation is like this:

20kg/40mg=50,000 and 50,000x2(sugar solution)=100,000

So the number of foraging trips should be 100,000 instead of 1 million. Do I miss something?

Thanks in advance!