How do I set loop such that a core in my PC do half while the other the other half in R

  arima, parallel-processing, r, windows

I have R scrip that simulates ARIMA data and check the same data 100 times for ARIMA order ARIMA(p, d, q). I have 2 core on the system CPU, how can I give an R command for a core to compute 1 to 50 while the second core to compute 51 to 100 simultaneously and then combine the result so that.

  for (i in 1:100) {
    a <- arima.sim(n = 50, model=list(ar = 0.8), sd = 1)
    b <- arimaorder(auto.arima(b, ic = "aicc"))

I am using windows 10 64 bits

Source: Windows Questions