The sum of the last four digits of Xiao Ming's phone number is 6, and there is no 0 in the four numbers. Guess the last four digits. What is the probability of guessing correctly once?
小明家电话号码后4位数字之和是6，四个数中无0，猜后四位，一次猜对的可能性是多少．
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<result>1/10 = around 0.1</result>