Ahardware salesman measures the mass of a box containing
1000
washers. the mass is
0.4168
kg
. what is the mass of a single washer in milligrams? write your answer as a decimal.

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.