My calculations: (edited after Woofie pointed out my mistake)

Surface area of the sphere: 6 inches (2,54 cm/inch) = 15,24 cm diameter
--> A = 4 (~3,14).(r²) = 4 (~3,14). (15,24 cm/2)² = 729,66 cm²

Surface area of the jewels: A = (~3,14)(0,5 cm/2)² = 0,196 cm²

--> number of jewels: 729,66 cm²/0,196 cm² = ~3722 jewels. Mind you that this is an estimate. You'll propably need less since the jewels won't line up perfectly and there's space in between the circular jewels.

Anyone correct me if I'm wrong.

Lol .. thanks Lee-Roy! 1,871 jewels is about 1, 771 too many! Nice to know there is someone to fall back on when you have these complicated equations to solve.

Ha! Interesting how we're all coming up with different numbers. Gets fun since we're mixing inches and mm.

Lee-Roy, not to quibble, but for the surface area of the jewels, I come up with .19625, not .39:
.5 cm/2 = .25
.25 x .25 = .0625
3.14 x .0625 = .19625
We differ by a factor of 2. Thoughts?

woofie said:Ha! Interesting how we're all coming up with different numbers. Gets fun since we're mixing inches and mm.

Lee-Roy, not to quibble, but for the surface area of the jewels, I come up with .19625, not .39:
.5 cm/2 = .25
.25 x .25 = .0625
3.14 x .0625 = .19625
We differ by a factor of 2. Thoughts?

You are absolutely right Woofie

My head hurts.

Pay no mind to us, Anne. Just gaze into the nice, shiny gazing ball...

Ok .. gazing away.