The integer number 130 has this decomposition into the product of these prime numbers: 130 =. . = . . . Note that the indexes are 1 for 2, 1 for 5 and 1 for 13. Now add 1 to each of the three indexes: 1 + 1 = 2 (for 2); 1 + 1 = 2 (for 5); 1 + 1 = 2 (for 13). Now the number of all divisors for 130 (including 1 and including 130 itself) is the product 2*2*2 = 8. They are 1 = , 2 = , 5 = , 10 = , 13 = , 26 = , 65 = , 130 = .