Question

A hardware salesman measures the mass of a box containing

Answer 1

Step $1$

find the mass of a single washer

Divide the total mass by the number of washers

$\frac{0.4168}{1000} =0.0004168\ Kg$

$0.0004168kg=4.168*10^{-4} kg$

Step $2$

Convert kg to mg

we know that

$1 kg=1*10^{6} mg$

so

$4.168*10^{-4}*10^{6} =4.168*10^{2}mg=416.8 mg$

therefore

the answer is

$416.8 mg$

Answer 2

In this question, the box with 1000 washers has 0.4168kg mass. Then, to find the mass of a single washer you need to divide the mass with the number of washers. Then, you need to convert the unit into milligrams(1kg= 10^6mg)
It would be 0.4168 kg / 1000 * 10^6 milligram/kg= 4168mg.