diff --git a/rbms/rbm_equations/rbm_template_gavin.ipynb b/rbms/rbm_equations/rbm_template_gavin.ipynb
index 600a332..f1daa96 100644
--- a/rbms/rbm_equations/rbm_template_gavin.ipynb
+++ b/rbms/rbm_equations/rbm_template_gavin.ipynb
@@ -65,7 +65,8 @@
       "$ = e^{\\mathbf{c}^T \\cdot \\mathbf{x}} / Z \\sum \\limits_{h_0 \\in \\{0,1\\}} ... \\sum \\limits_{h_{(H-1)} \\in \\{0,1\\}} \\prod\\limits_{j=1}^{H-1} \\exp{(h_j \\mathbf{W}_j \\cdot \\mathbf{x} + b_j h_j)} (1  + \\exp{(\\mathbf{W}_H \\cdot \\mathbf{x} + b_H}))$\n",
       "\n",
       "\n",
-      "Repeat this trick for each sum from $H-1$ down to $0$.\n",
+      "Repeat this trick for each sum from $H-1$ down to $1\n",
+      "$.\n",
       "\n",
       "$ = e^{\\mathbf{c}^T \\cdot \\mathbf{x}} / Z \\times (1 + \\exp{(\\mathbf{W}_1 \\cdot \\mathbf{x} + b_1})) \\times ... \\times (1  + \\exp{(\\mathbf{W}_H \\cdot \\mathbf{x} + b_H}))$\n",
       "\n",
@@ -84,7 +85,11 @@
       "$ p(\\mathbf{h}|x) = \\prod_j p(h_j | x) $ \n",
       "\n",
       "$ p(h_j = 1 | x) = \\dfrac{1}{ 1 + e^{-(\\beta_j + W_j.x)} } $  \n",
-      "$ p(x|h) $\n"
+      "$ p(x|h) $\n",
+      "\n",
+      "$ \\sum\\limits_{i=1}^{N} 1 = 1 + 1 + ... + 1 $ ($N$ times)\n",
+      "\n",
+      "$ \\sum\\limits_{i=1}^{3} i = 1 + 2 + 3 = 6$"
      ]
     },
     {