1.5, 2.3, 3.1, 3.9, ..?
Choose one:
A) 0.6
B) 0.8
C) 0.4
D) 0.24
E) 0.15
1.5+0.8= 
<gadget id="calculator">1.5+0.8</gadget>
<output>2.3</output>
2.3   2.3+0.8= 
<gadget id="calculator">2.3+0.8</gadget>
<output>3.1</output>
3.1   3.1+0.8= 
<gadget id="calculator">3.1+0.8</gadget>
<output>3.9</output>
3.9   3.9+0.8= 
<gadget id="calculator">3.9+0.8</gadget>
<output>4.7</output>
4.7   ANSWER:0.8
<result>B</result>
1.5, 2.3, 3.1, 3.9, ..?