There is a four-digit number, add a decimal point after one of its digits to get a decimal, then add this decimal to the original four-digit number, the result is 4003.64, find the four-digit number.
有一个四位数，在它的某位数字后加上一个小数点，得到一个小数，再把这个小数和原来的四位数相加，得数是4003.64，求这个四位数．
<gadget id="calculator">100 + 1</gadget>
<output>101</output>

<gadget id="calculator">4_003.64 / 101</gadget>
<output>39.64</output>

<gadget id="calculator">39.64 * 100</gadget>
<output>3_964</output>

<result>3_964</result>