What is the sum of 7 * 10 ^ - 8 and 6 * 10 ^ - 8 ?

(1 pc
13 * 10 ^ 8
1.3 * 10 ^ - 7
13 * 10 ^ - 16

The sum of 7 * 10 ^ - 8 and 6 * 10 ^ - 8 is 13 * 10 ^ - 8.