MCNP -- What is meant by 2M and 20R?

[Anisur Rahman]

TL;DR Summary

MCNP Importance

What is meant by 2M and 20R here?

 

[Alex A]

Welcome to PF!

M I didn't know, but I and R are common. I means interpolate, R means repeat and M turns out to mean multiply.
So in any long list of numbers,
5 20M 20M
Would be the same as,
5 100 2000
and
7 8R
Would be the same as,
7 7 7 7 7 7 7 7 7
and
1 8I 10
Would be the same as,
1 2 3 4 5 6 7 8 9 10
(I think, I make a lot of off by one errors using I, it's not in your question but it saves soooo much effort writing tally bins you should know it)

 

[Anisur Rahman]

Thank you so much!