Here are the steps to solve this problem:
1. Convert both lists of numbers to sets:
set1 = {11, 2, 3, 4, 15, 6, 7, 8, 9, 10}
set2 = {15, 2, 3, 4, 15, 6}
2. Find the intersection of the two sets:
intersection = set1.intersection(set2)
3. The number of elements in the intersection is the number of similar elements:
similarity = len(intersection)
4. Print the result:
print(similarity)
The similarity between the two sets is 4, since they both contain the elements {2, 3, 4, 15}.