So for our kids, who are still quite young, instead of opening an entire other savings account for them, we decided to do “virtual” savings accounts....
interest rates are usually an annual rate and accrue monthly. You seem to have applied the interest percentage of 1% to every deposit which is incorrect. Each deposit should gain that amount every year. For example, if you deposited $10 last year now it would be $10.10. If you deposited $10 2 years ago it would now be $10.201 due to the interest compounding.
Calculating Interest on a "Virtual" Savings Account
So for our kids, who are still quite young, instead of opening an entire other savings account for them, we decided to do “virtual” savings accounts....