» Summing Numerical Substrings

Problem:

List1 (column A) contains text values, each of which consists of a number with the letter "T" at the beginning.
We want to extract the numbers from each string and sum them.

Solution:

Use the SUM, VALUE, and SUBSTITUTE functions as shown in the following Array formula:
{=SUM(VALUE(SUBSTITUTE(A2:A6,"T","")))}