The LEFT function allows you to extract a string from a cell with a specific number of characters, however, if you extract a number from a text string the output will also be a text string.
You can see that above, the numbers in column C are aligned to the left indicating that Excel sees them as text strings.
They need to be numbers if you, for example, want to sum the values using the SUM function.
You can easily convert the text string to numbers by multiplying the LEFT function with 1.
The values in column C are now aligned to the right indicating they are now numbers.
Download Excel *.xlsx file
LEFT function for numbers.xlsx