title: 4 bit Year and decade counter
body: <p>So I came across this problem and I can't figure an elegant solution, maybe someone can point me in the right direction. 
  Say I have a <em>4 bit</em> <code>counter</code> (so it can count from <code>0-15</code> in decimal) for number of years elapsed. On year <code>16</code>, the year counter will overflow and reset back to <code>0</code>, on year <code>17</code> it will be <code>1</code> and so on. I also have a <code>decade</code> counter that will have the value <code>1</code> for years <code>10</code> through <code>19</code>, value <code>2</code> for years <code>20</code> through <code>29</code> and so on. 
  How can I get the total number of years elapsed if I have the yearCounter and decadeCounter information? </p>
  
  <p>E.g. <code>decade = 1</code> and <code>counter = 2</code>; <code>year = 18</code>.</p>
  
  <p>Is there a <em>name</em> for this kind of problem? And is there a function that can calculate the number of <code>year</code>s from these <code>counter</code>s up to <code>decade</code> overflows?</p>