Expression cannot display inaccurate result when query more than 2

Can somebody help me, I having problem when using expression 3 query. For my case, the value is (0.870X1.02X1)*100= 88.74. But, when I use the expression function, it get 97.4. Can somebody?

Duplicate of :
https://community.grafana.com/t/expression-grafana/81416

Therefore closing this one