Introduction
In this interview, Tuyet reads some of the decimal numbers in the conventional way ("point digit digit") but further probing reveals confusion over the names of the columns. She uses tens instead of tenths, and hundreds instead of hundredths. She knows that some of her ideas are in conflict with others.

Comments: Text in italics
Interviewer: Text in red
Tuyet: Text other colour

Interviewer:
Could you please read out the numbers on these cards?

Tuyet:
Oh point 4

Correct, zero point four is preferable. Many teachers encourage beginners to read this as four tenths.

Tuyet:
nine point seven

Correct, either this or nine and seven tenths.

Tuyet:
Oh point one six three or sometimes you can say 1 ten 6 hundreds and 3 thousands but I'm not sure because that can be three thousand six hundred and ten, too.

Tuyet uses incorrect names for the columns and reveals that this causes confusion for her.

Tuyet:
Point oh two five or maybe five thousand two hundred

Again, Tuyet reads the decimal in two ways indicating her mirror image labelling.

Tuyet:
Oh point nine seven or seven hundred and ninety

Again....

Tuyet:
Four point two six or six hundred and twenty four sometimes

Again....

Interviewer:
If a friend asked you to explain what this last number means, what could you say to help them?

Tuyet:
Well, the 4 means there are 4 wholes and then...

Tuyet:
...I think that maybe is the tens and...

Note not tenths...

Tuyet:
... that this is the, ummm, hundreds.

...and not hundredths.