Answer
Someone might make that mistake because place values to the left of the decimal begin with "ones". However, numbers to the right of a decimal indicate a fraction, with the place value as the denominator of the fraction. A denominator of 1 would not be a fraction, so the first place value to the right of the decimal is "tenths".
Work Step by Step
The numbers to the right of the decimal indicate a fraction, with their place value as the denominator. For example, the number 2.3 is written as two and three tenths . The 2 is a whole number in the "ones" place to the left of the decimal. If the first place value to the right of the decimal were "oneths", the 3 would have a denominator of 1, which would result in a whole number: 3/1. Therefore, the place value to the right of the decimal is "tenths" so the denominator is 10: 3/10.
