銀行利率計算

1: simple interest vs compounded interest

e.g.

if interest rate = 5% per annum

you deposit HK$1,000 into the bank

after 1 yr

simple interest: you can get back = HK$1,000 x (1 + 5%) = HK$1,050.00

compound interest bi-annually: you can get back = HK$1,000 x [(1 + 5% / 2) ^ 2] = HK$1,050.63

compound interest quarterly: you can get back = HK$1,000 x [(1 + 5% / 4) ^ 4] = HK$1,050.95

compound interest monthly: you can get back = HK$1,000 x [(1 + 5% / 12) ^ 12] = HK$1,051.16

compound interest weekly: you can get back = HK$1,000 x [(1 + 5% / 52) ^ 52} = HK$1,051.25

compound interest daily: you can get back = HK$1,000 x [(1 + 5% / 365) ^ 365] = HK$1,051.27

compound interest continuous: you can get back = HK$1,000 x [e ^ (5%)] = HK$1,051.27


2:
e.g.

if interest rate = 3% per annum

you deposit HK$2,000 into the bank

after 2 yr

simple interest: you can get back = HK$2,000 x [(1 + 3%) ^ 2] = HK$2,121.80

compound interest bi-annually: you can get back = HK$2,000 x [(1 + 3% / 2) ^ 4] = HK$2,122.73

compound interest quarterly: you can get back = HK$2,000 x [(1 + 3% / 4) ^ 8] = HK$2,123.20

compound interest monthly: you can get back = HK$2000 x [(1 + 3% / 12) ^ 24] = HK$2,123.51

compound interest weekly: you can get back = HK$2,000 x [(1 + 3% / 52) ^ 104} = HK$2,123.64

compound interest daily: you can get back = HK$2,000 x [(1 + 3% / 365) ^ 730] = HK$2,123.67

compound interest continuous: you can get back = HK$2000 x [e ^ (2 x 3%)] = HK$2,123.67