Let's get this math done. We have 13 and we're going to multiply it by 15. This is the same as taking 13 and adding it to itself 15 times.
Step 1: 0 + 13 = 13
Step 2: 13 + 13 = 26
Step 3: 26 + 13 = 39
Step 4: 39 + 13 = 52
Step 5: 52 + 13 = 65
Step 6: 65 + 13 = 78
Step 7: 78 + 13 = 91
Step 8: 91 + 13 = 104
Step 9: 104 + 13 = 117
Step 10: 117 + 13 = 130
Step 11: 130 + 13 = 143
Step 12: 143 + 13 = 156
Step 13: 156 + 13 = 169
Step 14: 169 + 13 = 182
Step 15: 182 + 13 = 195

So, 13*15 = 195