public function coerce($numeratorUnits, $denominatorUnits)
{
return new SassNumber(($this->isUnitless() ? $this->value : $this->value * $this->coercionFactor($this->numeratorUnits, $numeratorUnits) / $this->coercionFactor($this->denominatorUnits, $denominatorUnits)) . join(' * ', $numeratorUnits) . (!empty($denominatorUnits) ? ' / ' . join(' * ', $denominatorUnits) : ''));
}