Perl | Math::BigInt->bfac() method

Math::BigInt module in Perl provides objects that represent integers with arbitrary precision and overloaded arithmetical operators. bfac() method of Math::BigInt module is used to calculate factorial of a number stored as BigInt object.

Syntax: Math::BigInt->bfac() Parameter: None Returns: a normalised BigInt object whose value represents the factorial of the given number.

Example 1: Use of Math::BigInt->bfac() method

perl

#!/usr/bin/perl 

# Import Math::BigInt module
use Math::BigInt;

$num = 5;

# Calculate the factorial of
# the above specified number

# Create a BigInt object
$x = Math::BigInt->new($num);

# Use Math::BigInt->bfac() method
# to calculate factorial
$factorial = $x->bfac();

print "Factorial of $num : $factorial\n";


$num = 10;

# Calculate the factorial of
# the above specified number

# Create a BigInt object
$x = Math::BigInt->new($num);

# Use Math::BigInt->bfac() method
# to calculate factorial
$factorial = $x->bfac();

print "Factorial of $num : $factorial\n";

Output:

Factorial of 5 : 120
Factorial of 10 : 3628800

Example 2: Use of Math::BigInt->digit() method to count digits in factorial of big numbers

perl

#!/usr/bin/perl 

# Import Math::BigInt module
use Math::BigInt;

$num = 100;

# Calculate the factorial of
# the above specified number

# Create a BigInt object
$x = Math::BigInt->new($num);

# Use Math::BigInt->bfac() method
# to calculate factorial
$factorial = $x->bfac();

# Print the factorial
print "Factorial of $num : $factorial \n";

# Print count of digits in factorial
$count = $factorial->length();
print "Count of digits in factorial : $count";

Output:

factorial of 100 : 93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000 
Count of digits in factorial : 158

Example 3: Use of Math::BigInt->digit() method to calculate value of nCr.

perl

#!/usr/bin/perl 

# Import Math::BigInt module
use Math::BigInt;

# Value of n
$n = 5;

# Value of r
$r = 3;


# Create BigInt objects 
$x = Math::BigInt->new($n);
$y = Math::BigInt->new($r);
$z = Math::BigInt->new($n - $r);


# calculate nCr using 
# formula n! / (r! * (n-r)!)
$nCr = $x->bfac() / ($y->bfac() * $z->bfac());


# Print calculated value of nCr
print "Value of ${n}C${r} : $nCr \n";


# Value of n
$n = 50;

# Value of r
$r = 15;


# Create BigInt objects 
$x = Math::BigInt->new($n);
$y = Math::BigInt->new($r);
$z = Math::BigInt->new($n - $r);


# calculate nCr using 
# formula n! / (r! * (n-r)!)
$nCr = $x->bfac() / ($y->bfac() * $z->bfac());


# Print calculated value of nCr
print "Value of ${n}C${r} : $nCr \n";

Output:

Value of 5C3 : 10 
Value of 50C15 : 2250829575120

Perl | Math::BigInt->bfac() method

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