Another scenario where the use of 'and' in a series of numbers is unclear to me is in explaining temperatures in Fahrenheit, i.e. 'one hundred and three degrees'. Though I generally avoid correcting people, when patients relay their temperature as such, I clarify their intended meaning. For young or old, the intent can be 100.3 or 103.0, interestingly. This is unlikely an issue in other fields of work and in Brittish or Canadian English.
Otherwise, I also was taught in grade school/primary school in Northern California,that the use of 'and' in a series of numbers indicated a decimal or preceded a fraction. For '150', both with and without 'and' sound clear to me. In common speech, I would rarely be confused.

Another scenario where the use of and in a series of numbers is unclear to me is in explaining temperatures in Fahrenheit, like for example one hundred and three degrees.

Though I generally avoid correcting people, when patients relay their temperature as such, I clarify their intended meaning. For young or old, the intent can be 100.3 or 103.0, interestingly. This is unlikely an issue in other fields of work and in British or Canadian English.

Otherwise, I also was taught in grade school/primary school in Northern California that the use of and in a series of numbers indicated a decimal or preceded a fraction. For 150, both with and without and sound clear to me. In common speech, I would rarely be confused.