I want to run 1000 iterations on some numbers automatically. I need the random numbers to update on each iteration, But F9 CANNOT do this. Do I need a monte carlo simulation add-in ?

F9 can run 1000 iterations automatically but it WONT update the random numbers so its really only like 1 iteration. Only when E1>=6 does it iterate 1000 times.

example.

cell A1:A10 =RAND()
cell B1:B10 =SUM(RANDBETWEEN(0,1))

cell E1 =SUM(B1:B10)
cell E2 =IF(E1>=6,1,0)
cell E3 =IF(E2=0,E3,E3+E2)

set tools > iterations to "1000" and calc. to "automatic" and you will see