diff --git a/fmmd_concept/fmmd_concept.tex b/fmmd_concept/fmmd_concept.tex
index ed58dba..4d59bc4 100644
--- a/fmmd_concept/fmmd_concept.tex
+++ b/fmmd_concept/fmmd_concept.tex
@@ -180,6 +180,9 @@ failure mode behaviour for say, differnet ambient pressures or temperatures.
 If $E$ is the number of applied states or environmental conditions to consider
 in a system, the job of the bottom-up analyst is complicated by a cross product factor again 
 $(N-1) \times N \times K \times E$.
+If we put some typical very small embedded system numbers into this, say $N=100$, $K=2.5$ and $E=10$
+we have $99 \times 100 \times 2.5 \times 10 = 247500 $.
+To look in detail at a quarter of a million test cases is obviously impractical.
 
 If we were to consider multiple simultaneous failure modes
 we have yet another complication cross product.