The difference between the four numbers is (1/40), and their ratio is 1:3:5:7. What is the smallest number among these four numbers?
四个数依次相差(1/40)，它们的比是1：3：5：7，这四个数中最小的数是多少．
<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">1 + 3 + 5 + 7</gadget>
<output>16</output>

<gadget id="calculator">7 / 16</gadget>
<output>7/16 = around 0.4375</output>

<gadget id="calculator">5 / 16</gadget>
<output>5/16 = around 0.3125</output>

<gadget id="calculator">(7/16) - (5/16)</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/40) / (1/8)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 16</gadget>
<output>1/16 = around 0.0625</output>

<gadget id="calculator">(1/5) * (1/16)</gadget>
<output>1/80 = around 0.0125</output>

<result>1/80 = around 0.0125</result>