Hello, The first writing of my previous formulas was not very clear .. Their writing is more appropriate in introducing infinite limits. We will have: Pi=Limit(2^(n+5/2)*sqrt(1-1/(2^(2^(-n-1))*(product((2-1/(cos(Pi*2^(-i-2)))^2)^(2^(i-1)),i=1..n))^(1/2^n))),n=infinity); Pi=Limit(2^(n+5/2)*sqrt(1-1/(2^(2^(-n-1))*(product((1-tan(Pi*2^(-i-2))^2)^(2^(i-1)),i=1..n))^(1/2^n))),n=infinity); Pi=2^(n+5/2)*sqrt(1-1/(2^(2^(-n-1))*(product(2^(2^(i-1))/(1/cos(Pi*2^(-i-1))+1)^(2^(i-1)),i=1..n))^(1/2^n))); Pi/4=Limit(sqrt(3*2^(2*n+1)-sqrt(3)*2^(4*n+2)*sqrt(2^(-2^(-n-1)-4*n-1)/(product((1-tan(Pi*2^(-i-2))^2)^(2^(i-1)),i=1..n))^(1/2^n)+2^(-4*n-2))),n=infinity); Pi/4=Limit(sqrt(3*2^(2*n+1)-sqrt(3)*2^(4*n+2)*sqrt(2^(-2^(-n-1)-4*n-1)/(product((2-1/(cos(Pi*2^(-i-2)))^2)^(2^(i-1)),i=1..n))^(1/2^n)+2^(-4*n-2))),n=infinity); Best regards.