The overall risk score is the Threat (in the range 1-5) times the Safeguard (in the range 5-1) divided by five. So there are 25 possible values:

Threat Safeguard Score

1 1 0.2 
1 2 0.4 
1 3 0.6 
1 4 0.8 
1 5 1 
2 1 0.4 
2 2 0.8 
2 3 1.2 
2 4 1.6 
2 5 2 
3 1 0.6 
3 2 1.2 
3 3 1.8 
3 4 2.4 
3 5 3 
4 1 0.8 
4 2 1.6 
4 3 2.4 
4 4 3.2 
4 5 4 
5 1 1 
5 2 2 
5 3 3 
5 4 4 
5 5 5

Anything less than 1 will show up as a 1. So you'll only see the following possible meaningful values.