How to calculate commulative interest.Give me in detail formulae for all calculation of regarding interest

if you owe someone 100 bucks and there is a cumulative interest rate of 10%, and you can't pay until 3 months after due date, this must be the computation:
after the first month 100+10=110
after the second month 110+11=121
after the third month 121+12.1=133.10

so you have to pay 133.10 bucks

if it's none cumulative, you only have to pay 130.
since computation would only be
100 + [3 months x 100(10%)] =130+

10 comes from 10% of 100
11 comes from 10% of 110
12.1 comes from 10% of 121