diff --git a/installation_pe1rxf-aprs-server.txt b/installation_pe1rxf-aprs-server.txt
index ba04443..263cb99 100644
--- a/installation_pe1rxf-aprs-server.txt
+++ b/installation_pe1rxf-aprs-server.txt
@@ -220,6 +220,11 @@ sudo visudo
     marcel ALL = (root) NOPASSWD: /usr/sbin/kissparms
 
 ---
+Install command line calculator
+
+sudo apt-get install bc
+
+----
 
 Install software from PE1RXF (meezenest.nl/mees):