It is known that a=2*3*3*5, b=2*2*3*3*5, what is the greatest common factor of a and b?
已知a=2*3*3*5，b=2*2*3*3*5，a和b的最大公因数是多少？
<gadget id="calculator">2 * 3 * 3 * 5</gadget>
<output>90</output>

<result>90</result>