title: Is `u32`/`i32` suggested even on limited range number case?
body: <p>Should we use <code>u32</code>/<code>i32</code> or it's lower variant (<code>u8</code>/<code>i8</code>, <code>u16</code>/<code>i16</code>) when dealing with limited  range number like "days in month" which ranged from 1-30 or "score of a subject" which ranged from 0 to 100? Or why we shouldn't?</p>
  
  <p>Is there any optimization or benefit on the lower variant (i.e. memory efficient)?</p>