Why 0.90 is between 0.9 and 0.91?

The decimal 0.90 can be expressed as 0.9 with an additional placeholder for the tenths digit. Similarly, the decimal 0.91 is one hundredth greater than 0.90. Therefore, 0.90 falls between 0.9 and 0.91 on the number line due to its position as a value that is greater than 0.9 but less than 0.91.