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# Basic Math/Calculating interest

Question
QUESTION: A short term loan of 50,000 is borrowed for 35 weeks at an interest rate of 18.5% p.a calculate the interest.

ANSWER: Sure, but I am not familiar with "p.a"...what is that?

---------- FOLLOW-UP ----------

QUESTION: P. a is per anuam yearly interest

OH...OK!

One more question (forgot to ask before)...what is the compounding period?

If it is weekly, then the future value of the loan is:
50,000(1+0.185/52)^35 = 56,617.68, so the interest would be 56,617.68 - 50,000 = 6,617.68

The formula for future value is: P(1 + r/n)^(n*t)
where P = principal (amount), r=APR, n=# of compounding periods/year, t=time

Abe

Basic Math

Volunteer

#### Abe Mantell

##### Expertise

Hello, I am a college professor of mathematics and regularly teach all levels from elementary mathematics through differential equations, and would be happy to assist anyone with such questions!

##### Experience

Over 15 years teaching at the college level.

Organizations belong to
NCTM, NYSMATYC, AMATYC, MAA, NYSUT, AFT.

Education/Credentials
B.S. in Mathematics from Rensselaer Polytechnic Institute
M.S. (and A.B.D.) in Applied Mathematics from SUNY @ Stony Brook