The principle of positive and negative signs is all unified in a specific problem
1. Based on our company's bank account
- The inflow bank account is + If you have money into the bank account, others will pay you
- Outgoing bank account is - money goes in and out of the bank account and you pay others
- Based on our company's safe deposit box
Incoming bank account this time is - Outgoing bank account this time is +
Suppose you're buying a house and you want to figure out how much you'll need to pay each month for a $180,000 mortgage with a 30-year term and 6% APR (the equal-payment method). Then the input formula is:
=PMT(6%/12,12 30,180000)
The result is:
￥-1,079.19
￥180,000 in the above formula is handled from the perspective of the borrower with a positive sign instead of a negative sign. This result is a negative number, which means that it will take ￥-1,079.19 per month in the future to be equal to the current borrowed amount of ￥180,000, which is equal.
The same above problem, from the perspective of the lender's bank, can be described as:
Suppose a customer wants to buy a house, and the bank wants to calculate the amount of mortgage loan with a loan amount of ￥180,000, a term of 30 years, and an annual interest rate of 6%. How much money you need to get from the client each month (equal debt service method). Then the input formula is:
=PMT(6%/12,12 30,-180000)
The result is:
￥1,079.19
The ￥180,000 in the above formula uses a negative sign instead of a positive sign (indicating that ￥180,000 is the investment amount), only this result It is a positive number, indicating that it will take ￥1,079.19 per month in the future to be equal to the current loan amount of ￥180,000, which is equal.
In short, according to their own purpose to determine the symbol.
Another example:
Say you're saving for a vacation. If you have $500 in your account and you plan to save $200 per month at 6% APR in the future, how much money will you have in 10 months? Then enter the following formula:
=FV(6%/12,10,-200,-500)
The result is:
￥2,571.175348
The reason why both ￥-200 and ￥-500 in the formula are negative signs means that they are all your investment amounts (or cash outflows in other words).