Excel ROUNDUP, ROUNDDOWN and ROUND functions
In the previous example we calculated the return on investment by using the power function. If you look at the results of the calculation on column D, you'll see that they show 5 digits after the decimal point.
While showing numbers after the decimal point is certainly more precise, it also makes reading the sheet much harder because of all those extra numbers.
One of the ways to eliminate (or reduce) the digits after the decimal point is to use the ROUNDUP(), ROUNDDOWN() and ROUND() functions.
As you probably gathered from its name, the ROUNDUP() function will round any given number up to the next round number.
What's interesting is that ROUNDUP() also lets round up to a specific number of decimal points. That's done by passing the number of decimal points you want to round up to as the second parameter (0 meaning to round up to the closest whole number, 1 meaning there will be one digit after the decimal point, and so on).
=ROUNDUP(18.23,0) will return 19
=ROUNDUP(18.23,1) will return 18.3
The ROUNDDOWN() acts exactly the same way as the ROUNDUP() function except it will round the number down to the previous round number (with a specified number of digits).
=ROUNDDOWN(18.23,0) will return 18
=ROUNDDOWN(18.23,1) will return 18.2
The ROUND() function will round to the closest number (given a specific number of digits).
=ROUND(18.23,0) will return 18
=ROUND(18.51,0) will return 19
What do you think will the function =ROUND(18.5,0) return?
Will it return 19 or will it return 18?
Open Excel and check if your answer was correct.