<h1>простенький калькулятор</h1>

<input type="text" placeholder="Введите цифру">

+ 

<input type="radio" id="five"  name="radio">
<label for="five">
5</label>

<input type="radio" id="six"  name="radio">
<label for="six">
6</label>

<input type="radio" id="seven" name="radio">
<label for="seven">
7</label> 

+

<select id="secector">
<option>50</option>
<option>60</option>
<option>70</option>
<option>80</option>
</select>

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