The greatest common divisor of three natural numbers is 17, and the least common multiple is 204. It is known that two of the numbers are 51 and 102, so what is the third number?
三个自然数的最大公约数是17，最小公倍数是204，已知其中两个数是51和102，那么第三个数是多少．
<gadget id="calculator">17 * 4</gadget>
<output>68</output>

<result>68</result>