From the 30 natural numbers 1 to 30, two different numbers are taken each time so that their sum is a multiple of 4. How many different ways are there?
从1～30这30个自然数中，每次取两个不同的数，使它们的和是4的倍数，共有多少种不同的取法？
<gadget id="calculator">3 / 3</gadget>
<output>1</output>

<gadget id="calculator">7 * 8</gadget>
<output>56</output>

<gadget id="calculator">6 + 5 + 4 + 3 + 2 + 1 + 56 + 7 + 6 + 5 + 4 + 3 + 2 + 1</gadget>
<output>105</output>

<result>105</result>