src/CanvasArray.php
protected function pageNumberToKey($pageNumber)
    {
        if (isset($this->pagination[CanvasPageLink::CURRENT])) {
            return ($pageNumber - 1) * $this->pagination[CanvasPageLink::CURRENT]->getPerPage();
        }
        return false;
    }
protected function pageNumberToKey($pageNumber)
    {
        if (isset($this->pagination[CanvasPageLink::CURRENT])) {
            return ($pageNumber - 1) * $this->pagination[CanvasPageLink::CURRENT]->getPerPage();
        }
        return false;
    }
Convert a page number to an array key

@param int $pageNumber 1-indexed page number

@return int|false