Capital budgeting

A bank offers different bank accounts with different interest rates
Bank account 1 = 10% interest per year, interest calculated quarterly
Bank account 2 = 12% interest per year, interest calculated monthly
Bank account 3 = 1.2% interest per month
Bank account 4 = 3% interest per quarter

Solution:

1. (1+0.1/4) ^4-1 X 100 = 10.38%
2. (1+0.12/12) ^12-1 X 100 = 12.68%
3. (1+0.012) ^12-1 X 100 = 15.39%
4. (1+0.03) ^4 -1 X 100 = 12.55%

I don’t get it we have formula where R = (1 + i/n) ^ n -1

The first two solutions have been divided by “n”, but in the case of the last two (3 and 4) they did not divide by “n” (In the 3rd case it’s 12 and in the 4th case is 4). can you explain why?

thanks in advance