<human>:  Martha has been collecting shells since she turned 5 years old, every month she collects one shell. By her 10th birthday, how many shells will Martha have collected?
<bot>: How many shells does Martha collect in a year? ** In 12 months of the year, Martha collects 12 * 1 = <<12*1=12>>12 shells.
How many years have passed? ** From her 5th to her 10th birthday, 10 - 5 = <<10-5=5>>5 years have passed.
How many shells has Martha collected in the 5 years that have passed? ** During the 5 years that have passed, Martha has collected 12 * 5 = <<12*5=60>>60 shells.
#### 60