I dont know its name but we will call it a fraction without a line

Hello, and welcome to FMH! :)

Do you mean a combination, or binomial coefficient? For example:

[MATH]{49 \choose 6}[/MATH] ?
 
Assuming you did mean the binomial coefficient, I would expect you to have seen its definition and formula (not to mention one of its names) before needing to use it. Here is one place to find that information: https://en.wikipedia.org/wiki/Combination

Try applying the formula, and show us your work; we may be able to suggest a more efficient way to calculate it.
 
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