# Basic formulas

All formulas start with ‘=’.  If you enter a formula but the formula appears in the cell instead of the result, then try putting an equal sign in front of it.  Essentially you’re saying “the value in this cell equals the result of this formula.”

The simplest formula is ‘=a1’ or ‘=Foo’.  The most common use for this is when the cell you’re pulling from is not visible from your current location on the screen, but you want to see it next to what’s currently visible.  I also use it for repeating headers, such as when I’m listing the same five things for each month of the year.

The next most simple formulas have the basic operands everyone learned in grade school: plus, minus, times, and divide.  Usually times is ‘*’ and divide is ‘/’.

Examples:

=TotalPC + TotalMac could be the formula that that adds together the total number of PCs and the total number of Macintosh  computers in the inventory.

=MonthlyIncome – MonthlyOutgo could be the formula that calculates how much is left in the monthly budget.

=Principle * InterestRate could be the formula that calculates how much interest will accrue on a loan.

=TotalCost / Participants could be the formula that calculates how much each person participating in a given activity owes.

The last thing I’m going to introduce in this post is your friend and mine, the parenthesis ().  There are rules as to what order the elements of a formula are processed in, but I like making my life easier by using parenthesis to dictate the order if it’s important.  Anything inside the parenthesis gets processed before anything outside.  For example, (4 + 1) * 0 = (5) * 0 = 0, but 4 + (1 * 0) = 4  + (0) = 4.

Those the basic formula elements.  Using just those elements as building blocks it’s possible to get some pretty complex and useful results.  For example, the formula =MonthlyPayment – PreviousBalance * (APR /100/12) tells the user how much of a monthly payment is going towards the principle of a debt, instead of to interest.