After removing the fractional part from a decimal, an integer is obtained. The product of this integer plus the product of the original decimal multiplied by 4 is 21.2. What is the original number?
一个小数去掉小数部分后得到一个整数，这个整数加上原来的小数乘以4的积，和是21.2，原来这个数是多少．
<result>4.3</result>