What is the unit digit of the difference between the product of all prime numbers not exceeding 100 minus the product of all prime numbers not exceeding 60 and having a unit digit of 7?
不超过100的所有质数的乘积减去不超过60且个位数字为7的所有质数乘积所得之差的个位数字是多少．
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<result>9</result>