public int greatestProduct(String sNum) {
		int numLen = sNum.length();
		int greatestProduct = 0;
		int current = 0; //store current number for comparison 
		
		for (int i = 0; i < numLen - 4; i++) {
			current = getProduct(sNum, i);
			if (greatestProduct == 0) {
				greatestProduct = current;
			}
			else if (current > greatestProduct) {
				greatestProduct = current;
			}
		}
		return greatestProduct;
	}