The INT in the INT function is short for Integer. In the world of Mathematics, an integer is a whole number that can be positive, negative or zero. Similarly, the Excel INT function serves to round down numerical values to their nearest whole number. This means that positive numbers would be less positive and negative numbers would be more negative. For example, INT(5.8) would be round down to the number 5 whilst INT(-5.8) would be round down to the number -6.

## Syntax

The syntax for the INT function is

=INT(number)

The INT takes just one argument which is “number”, this must be a numerical value as using the formula on cells containing text values would result in a #Value error. Now, let’s look at some examples using the INT function

## INT Function Examples

We would divide this section into two, the first would be the round down of positive numbers, and the second, round down of negative numbers.

### INT function on Positive numbers

When the INT function is used on cells containing positive decimal numbers, the number is round down to the next lowest whole number:

=INT(7.52) // returns 7

=INT(7.99) // returns 7

### INT function on negative numbers

Using the INT function on negative decimal numbers however have an opposite effect, the round down away from zero, thereby making the number more negative.

=INT(-7.52) // returns 8

=INT(-7.99) // returns 8

## Practical use of the INT function

As with every other Excel function, I always ask myself: How do I apply this to real-life modeling? On the surface, you might ask yourself why you need to learn about this function. Well, there are many reasons, and one that comes to mind is the calculation of the age when combined with the YearFrac function.

Imagine that you have the result of a marketing survey downloaded from a system to an Excel file, and there is a column containing the respondents’ date of birth. In order to categorize respondents by age, you need to be able to calculate each respondent’s age. Remember, however, that you are only as old as your last birthday.

Calculating respondent’s age manually would involve having to check the current date vs date of birth of each respondent and then ascertaining their age at their last birthday. Imagine how long this would take depending on the number of respondents in your report. With a combination of the YearFrac, Today and INT functions, we can easily calculate each respondent’s age. Let’s see an example below:

To calculate the ages of the respondents, simply use the formula combination below: