How do you calculate precentages on a caculator?

Answer 1

Some calculators have special percentage keys, but I find it easier to just use normal multiplication or division, depending on the calculation. Here are three examples:

Q: If I put $5000 into a bank account, at an interest rate of 6%, how much interest do I earn?

A: 6% is equivalent to 0.06. You should be able to calculate this part in your head. 6% "of" 5000 means 0.06 x 5000. This is the calculation you type into your calculator.

Q: Let's say that in the previous problem, I am not interested in the interest earned, but in the total amount I can withdraw after one year. Of course you can add the interest to the capital, but a faster method is to multiply 5000 x 1.06 (i.e., adding one to the interest as a decimal).

Try it out; it's really easy!

Here are some sample problems, with answers to let you check your calculations.

a. 5% of 2000? Answer: 100

b. 7% of 300? Answer: 21

c. 2.5% of 20,000? Answer: 500

d. If you add 6% to 8000, how much do you get (in total)? Answer: 8480

e. If you add 3.5% to 4000, how much do you get? Answer: 4140

f. Initial capital is 5000; annual compound interest rate is 5%; how much money do you have after 3 years? (Hint: apply the factor 3 times). Answer: 5788.13