Suppose a and b are two unequal natural numbers, if their least common multiple is 72, how many different values can the sum of a and b have.
设a与b为两个不相等的自然数，如果他们的最小公倍数是72，那么a与b之和可以有多少种不同的值．
<gadget id="calculator">4 - 2</gadget>
<output>2</output>

<gadget id="calculator">11 + 3 + 2 + 1</gadget>
<output>17</output>

<result>17</result>