program define mcdisk
	clear all
	quietly set obs `1'
	gen x=2*runiform()
	gen y=2*runiform()
	quietly count if (x-1)^2+(y-1)^2<1
	display 4*r(N)/_N
end

. mcdisk 10000
3.1424

. mcdisk 1000000
3.141904

. mcdisk 100000000
3.1416253