diff --git a/10_introduction_to_artificial_neural_networks.ipynb b/10_introduction_to_artificial_neural_networks.ipynb
index 2a512a5..5808136 100644
--- a/10_introduction_to_artificial_neural_networks.ipynb
+++ b/10_introduction_to_artificial_neural_networks.ipynb
@@ -430,7 +430,7 @@
     "with tf.Session() as sess:\n",
     "    init.run()\n",
     "    for epoch in range(n_epochs):\n",
-    "        for iteration in range(len(mnist.test.labels)//batch_size):\n",
+    "        for iteration in range(mnist.train.num_examples // batch_size):\n",
     "            X_batch, y_batch = mnist.train.next_batch(batch_size)\n",
     "            sess.run(training_op, feed_dict={X: X_batch, y: y_batch})\n",
     "        acc_train = accuracy.eval(feed_dict={X: X_batch, y: y_batch})\n",
@@ -576,7 +576,7 @@
     "with tf.Session() as sess:\n",
     "    init.run()\n",
     "    for epoch in range(n_epochs):\n",
-    "        for iteration in range(len(mnist.test.labels)//batch_size):\n",
+    "        for iteration in range(mnist.train.num_examples // batch_size):\n",
     "            X_batch, y_batch = mnist.train.next_batch(batch_size)\n",
     "            sess.run(training_op, feed_dict={X: X_batch, y: y_batch})\n",
     "        acc_train = accuracy.eval(feed_dict={X: X_batch, y: y_batch})\n",