1 cm = 10 mm so 41.9 cm = 419 mm. Simple!
Firstly we convert mm to cm. i.e. 10mm is 1cm. The formula for the volume of a sphere is 4/3pir^3. R^3 is 1, x3.14159 x 4/3 is 4.19cm^3. You have 100, so that is 419cm^3 volume. As each cm^3 is .0082kg, 419cm^3 will equal 419x.0082kg. This is 3.434kg.
10 mm = 1cm 1 in = 2.54 cm 1 in = 25.4 mm
90 mm
16.5 mm
304.8 mm
8500 mm
135 mm.
6450 mm
100 mm
153 mm
760 mm
50.8 mm