Why didn't Molly Weasley remember the platform number?

Question

In the first Harry Potter book, Molly is seen asking her children "what platform number is it again?"

Heart hammering, Harry pushed his trolley after them. They stopped and so did he, just near enough to hear what they were saying. 'Now, what's the platform number?' said the boys' mother. 'Nine and three-quarters!' piped a small girl, also red-headed, who was holding her hand. 'Mum, can't I go...' 'You're not old enough, Ginny, now be quiet. All right, Percy, you go first.' (Harry Potter and the Philosopher's Stone, Chapter Six, "The Journey from Platform Nine and Three-Quarters")

Why didn't she remember on her own? She would have been bringing kids there for the past 10 or so years, not to mention her own years at Hogwarts.

Answer 1

The way it’s described in the books makes it sound like it was just a question for Ginny to answer:

“Now, what’s the platform number?” said the boys’ mother.

“Nine and three-quarters!” piped a small girl, also red-headed, who was holding her hand. “Mum, can’t I go…”

The boys go straight through the barrier, so they must be standing right next to it. It follows that Mrs. Weasley has led them to the right platform, so she does know what it is.

There’s no mention of her being flustered or frustrated (or at least, no more than you’d expect with Fred and George for sons) about being unable to find the platform.

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ETA: I’ve seen several comments saying that perhaps this was a movie thing; it isn’t. This is what Molly says in the film, which Harry overhears after talking to the station staffer:

…same every year of course, packed with Muggles! Come on: Platform Nine and Three-Quarters this way.

She doesn’t seem particularly flustered or concerned, except to keep Ginny close by her side, and to make sure they all get through the barrier safely. There’s never any question about what the platform number is.

Answer 2

This is probably for Ginny's benefit. Ginny will be starting at Hogwarts the next year, and Molly is asking a question to which she obviously knows the answer to, to see if Ginny can answer it.

She is basically quizzing Ginny, as parents often do. It would be absurd to think Molly doesn't actually know or remember the correct platform. With brooms, portkeys, Floo networks and Apparation, the Hogwarts train is probably the only train magic-born ever use.

And in the six years that Harry attended Hogwarts, the platform didn't change.

Answer 3

There's a strong possibility that she's genuinely trying to work out which platform they're going to be using. In the Pottermore moment on Platform 9 3/4, JKR notes that there were other "fractional platforms" that wizarding trains use to transport witches and wizards to various magical destinations.

It's quite feasible that in other years, the Hogwarts Express set off from a different platforms and she's looking for confirmation which platform they'll be departing from this time;

"In choosing the number of the concealed platform that would take young witches and wizards to boarding school, I decided that it would have to be a number between those of the Muggle platforms – therefore, it was clearly a fraction. This raised the interesting question of how many other fractional platforms lay between the whole-numbered platforms at King’s Cross, and I concluded that were probably quite a few.

Although these are never mentioned in the book, I like to think that it is possible to take a version of the Orient Express off to wizard-only villages in continental Europe (try platform seven and a half), and that other platforms may be opened on an as-required-basis, for instance for large, one-off events such as Celestina Warbeck concerts (see your ticket for details)."

Answer 4

What makes you think she didn't remember platform number? Parents (and other teaching figures) frequently ask questions whose answers they know, with the intended goal being for their children to provide the answer; it's a tool that helps the child remember facts.

It's like going to an amusement park and asking your kids "Okay kids, where did we park?" so your children remember where the car is if the family becomes separated.

Answer 5

The most likely answer is also the simplest (and least interesting). She probably forgot because she doesn't use it that often.

A number you use only once (or even twice) a year is easy to forget. I can never remember what local voting district (18 or 19?) I am in, for example. Who remembers their driver's license number?

OK, that's usually a long number, but what about your congressional district number? How about the street address of your school? These are all things that we tend to forget, not because they are hard to memorize, but simply because we don't use them that much, and on the annual or semi-annual occasion that we do, we can just look it up (or ask someone else), so it's not really worth trying very hard to remember long term.

Answer 6

I read about a conspiracy theory: She said it deliberately to attract Harry to his family (Dumbledore warned her about Harry) but conspiracy theories don't deserve attention, although this specific theory is interesting.

In my opinion, this is a REAL question, it's possible that in his epoch, the platform had a different number.

Answer 7

The truth is J.K. Rowling made mistakes in the book and she admitted to that. No one would forget the number as commented above. Even if you use it one time, you also go to Diagon alley one time a year but they do not forget that. The fact she grew up in a wizard family and that was always the way, than would be common knowadge for the wizard world as much as the Minster or Hogwarts.

She purposely put that in there to go with the story or made a simple mistake like the misnumber of Horcrux's. (There was 7, Harry was 8 and the snake was 9 yet 7 were destroy)