Checking and correcting CHI numbers | Cleaning up bad CHI numbers | Inferring data from a CHI number | The structure of a CHI number | Modulus-11 check | Changes to CHI numbers (August 2026): Inclusion of Modulus-10 check | Extracting sex from CHI | Extracting Date of Birth from CHI | Extracting age from CHI

Motivation | Creating percentages | Rounding | Rounding via as_percent + digits | Rounding via round() | Math with percent vectors | percent vectors and tidyverse | vectors and formatted tables | percent vectors and ggplot2