Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Calculation/Engineering.php
public static function BINTODEC($x)
    {
        $x = Functions::flattenSingleValue($x);

        if (is_bool($x)) {
            if (Functions::getCompatibilityMode() == Functions::COMPATIBILITY_OPENOFFICE) {
                $x = (int) $x;
            } else {
                return Functions::VALUE();
            }
        }
        if (Functions::getCompatibilityMode() == Functions::COMPATIBILITY_GNUMERIC) {
            $x = floor($x);
        }
        $x = (string) $x;
        if (strlen($x) > preg_match_all('/[01]/', $x, $out)) {
            return Functions::NAN();
        }
        if (strlen($x) > 10) {
            return Functions::NAN();
        } elseif (strlen($x) == 10) {
            //    Two's Complement
            $x = substr($x, -9);

            return '-' . (512 - bindec($x));
        }

        return bindec($x);
    }
public static function BINTODEC($x)
    {
        $x = Functions::flattenSingleValue($x);

        if (is_bool($x)) {
            if (Functions::getCompatibilityMode() == Functions::COMPATIBILITY_OPENOFFICE) {
                $x = (int) $x;
            } else {
                return Functions::VALUE();
            }
        }
        if (Functions::getCompatibilityMode() == Functions::COMPATIBILITY_GNUMERIC) {
            $x = floor($x);
        }
        $x = (string) $x;
        if (strlen($x) > preg_match_all('/[01]/', $x, $out)) {
            return Functions::NAN();
        }
        if (strlen($x) > 10) {
            return Functions::NAN();
        } elseif (strlen($x) == 10) {
            //    Two's Complement
            $x = substr($x, -9);

            return '-' . (512 - bindec($x));
        }

        return bindec($x);
    }
BINTODEC.

Return a binary value as decimal.

Excel Function:
BIN2DEC(x)

@category Engineering Functions

@param string $x The binary number (as a string) that you want to convert. The number
cannot contain more than 10 characters (10 bits). The most significant
bit of number is the sign bit. The remaining 9 bits are magnitude bits.
Negative numbers are represented using two's-complement notation.
If number is not a valid binary number, or if number contains more than
10 characters (10 bits), BIN2DEC returns the #NUM! error value.

@return string