Let $R_1$ and $R_2$ be relations on the set {1, 2, 3, ……. 50} such that $R_1=${ $(P,P^n)$ : P is prime and $n\ge 0$ is an integer} and  $R_2=$ { $(P,P^n)$ : P is prime and n = 0 or 1}. The number of elements in  $R_1$  is K and the number  of elements in $R_2$   is L. Then  $K+L=$

$P,P^n\in \{1,2,\mathrm{.....50}\}$ 
Now P takes the values 2, 3, 5, 7, 11, 13, 17, 23, 29, 31, 37, 41, 43 and 47
Elements in $R_1:(2,2^0)(2,2^1)\mathrm{........}(2,2^5)\to$ 6 elements
$(3,3^0)(3,3^1)(3,3^2)(3,3^3)\to$ 4 elements
$(5,5^0)(5,5^1)(5,5^2)\to$ 3 elements
$(7,7^0)(7,7^1)(7,7^2)\to$ 3 elements
$(11,{11}^0)(11,{11}^1)\to$ 2 elements
$(13,{13}^0)(13,{13}^1)\to$ 2 elements
$\begin{array}{l}.\\ .\\ .\\ .\\ .\end{array}$  
$(47,{47}^0)(47,{47}^1)\to$ 2 elements
Number of elements in $R_1=6+4+3+3+2+2\mathrm{.........}10times=36$  
Elements in $R_2:(2,2^0)(2,2^1)\to$ 2 elements
$(3,3^0)(3,3^1)\to$ 2 elements
$\begin{array}{l}.\\ .\\ .\\ .\\ .\end{array}$  
$(47,{47}^0)(47,{47}^1)\to$ 2 elements
Number of elements in $R_2=\left(15\right)\left(2\right)=30$  
$n\left(R_1\right)+n\left(R_2\right)=38+30=68$