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

AI Thread Summary
In the context of MCNP, "2M" and "20R" refer to specific notations where "M" stands for multiply, "R" for repeat, and "I" for interpolate. For example, "20M" indicates multiplying a number by 20, while "20R" means repeating a number 20 times. This shorthand simplifies the representation of long lists of numbers, making it easier to write tally bins. The discussion emphasizes the utility of these notations in reducing effort when dealing with numerical data. Understanding these terms is crucial for efficient communication in MCNP-related tasks.
Anisur Rahman
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What is meant by 2M and 20R here?
 
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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)
 
Thank you so much!
 

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