Every interview with you – by law – has to mention the occasions that you have to spell out rude words in the Countdown letters game. Is that a revealing comment on the British sense of humour?

It’s one of the reasons people like Countdown. The funniest ones for me – because you get such a range of people who watch, from kids to students to OAPs, stereotypically – are words like growler. Where old people won’t know there’s a funny connotation to it, but everyone around my age is going to be screaming. Damian, our producer, is not what you would imagine for Countdown at all: he’s from Blackpool, he’s a skinhead, wears a leather jacket with a skull on it, big Blackpool fan. But he’s also a Countdown champion and he’ll come up with the filthiest anagrams straight away. There’s definitely an underlying level of filth to Countdown.

A friend was on Countdown and the letters were AADHILOST: the other contestant made a five-letter word and he got seven with DAHLIAS. Apparently you walked over in the ad break and whispered, “You could have had SHITLOAD …”

That’s probably one from Damian. We do five shows a day, 15 shows in a row, so to make the day go faster you do look for the rude ones. The teasers and the conundrums, I don’t know how he gets away with some of them. One of them made the papers a while ago; the conundrum was “largebaps” – and it was “graspable”. But there’s been some terrible stuff.

Countdown recently entered the Guinness World Records for the most series of a TV game show: 70 series, more than 6,000 episodes. But very few television programmes feature maths – why is that?

There was the Brian Cox effect with popular science, but yeah, maths has lagged a little bit. More than other subjects there’s a myth that you have to be an absolute genius to be good at maths and to enjoy it, so I think it’s less accessible for people. Even the word “maths” makes people screw their face up. They do the maths face.

What’s the maths face?

I see the maths face quite a lot. It’s the blind panic that they have to do maths in front of people. It’s just fear and dread. There’s definitely a maths face – try it on someone.

So someone who is good at maths is seen to possess special powers?

The maths brain. I’m really interested in male and female brains and whether female brains or male brains are better at maths. You sit men and women down and give them a maths test and they will do fairly equally. Then you set up the same test, but with different people, and make them tick a box to say whether they are a man or a woman, and the women do significantly worse in the maths test than they did previously in a group set. There’s an ingrained mentality in our culture that women aren’t as good. Other places it doesn’t exist.

What can we learn from that?

Just to stop saying things that are going to influence kids. Stop saying that there’s a maths brain. Stop saying that girls aren’t as good. Stop pulling the maths face, because it has a big influence.

Why do you think you weren’t affected by the stereotyping?

I just wasn’t aware of it. The first time I remember people thinking of differences between girls and boys was when I got to uni. I went to an all-girls school and we had a really power-feminist headmistress and it wasn’t even a question if there was a difference, if anyone was better. But there was a definite shift from studying it at school to uni, so when you tell people that you are studying maths at uni, they are like, “Oh …”. Especially a blonde Essex girl.

Does this give boys an advantage?

I think girls have a different approach: boys are happy to get stuff wrong and girls want to do it properly the first time. That’s a big problem we have: girls are scared to fail, much more than boys are, so they don’t try as much, they don’t extend themselves.

It’s interesting, that we get a lot more male Countdown contestants than women and I think that’s the same thing about putting yourself out there. Men are not as scared to lose and they’ve got a lot more time to devote to, not exactly pointless things, but to being good at things like Countdown. Being good at Countdown is not going to help raise the kids or something like that.

You’re a judge for the Astellas Innovation Challenge, which asks children in Years 10 and 11 to invent an app for healthy living. Aged 15 or 16, might you have entered?

You know, I can see why people might find maths intimidating, because I’ve never done any coding, never seen anything like that. Not that this is a coding challenge, but they’ve known the internet since they were babies, so it’s just kind of inherent.

But you don’t have to be a coder, you can just come up with an idea. It could be something that helps you remember to take your tablets. It could be something that gets you out of bed for a morning. It could be something novel that gives you a vibration if you go near a chocolate bar.

Which health apps do you use ?

MapMyRide, because I’m a cyclist and I like the stats. And I used a Fitbit for a while. I liked that you had a target and I still do take the stairs instead of the lift at work, but I don’t wear it now. I had it on one day when I was training for Strictly and it was a 10-hour day and it was a Russian dance, so it was really busy. But when I checked how many steps I’d done, it said I was active when we went for lunch, and the rest of the time I was moderate or stationary.

At that point I thought, “Ah, this doesn’t work too well.” And once the stats are out, it’s kind of dead to me.

Would you describe yours as an accidental TV career?

Totally. I never did any public speaking at school, never did any performing. I just applied for Countdown because I liked the numbers game and used to watch it as a kid. I didn’t have anything to lose. It was the same thing with applying to Oxford: I’d never known anyone who’d been to Oxford, but didn’t have anything to lose.

So I finished my masters and I was applying for loads of different grad jobs and that one application form was much shorter. I didn’t have to write how I liked being part of a team and what my biggest challenge was or anything like that.

You have a masters degree in applied maths from Oxford. Is TV stimulating enough for you?

What else would I be doing that’s more satisfying? I did an internship at a hedge fund when I was at university, didn’t enjoy it, didn’t feel like I was doing anything good for anybody. I like doing things that scare me – and I get to do that a lot on TV.

Is that why you did Strictly Come Dancing?

I like doing different things. So, from doing Strictly I learned that I was a perfectionist. I got stage fright and actually had CBT [cognitive behavioural therapy]. The guy was brilliant: I didn’t realise I was a perfectionist, because I didn’t want things to be perfect and thought that’s what a perfectionist was. But it’s more that you are never satisfied with yourself.

How did that apply to the dancing?

You want to be the best and you always think you can be doing more. In some ways that will push you to do well and in other ways it will drive you insane forever. I’d never done dancing before. I wasn’t amazing, I wasn’t the worst, but I thought I was the worst. In my head I was never going to be able to achieve what I wanted to achieve, because I was never going to be perfect. So it’s just learning to have an achievable goal, a sense of what is a good outcome, because otherwise you are never satisfied. In victory, you think it’s a bit of luck and anything that goes badly is your fault.

Do you ever get nervous on Countdown?

Nah, I’m a maths geek, that’s the fun bit. And someone has done a really detailed analysis of my stats and they are really good. I’m good at maths games, I like the puzzle side of the newspaper. I’ve got different apps on my phone like 6 Numbers and A Clockwork Brain for brain training. I’m not ashamed!

You gave up presenting Channel Five’s The Gadget Show this year after three series. What was your favourite bit of kit you tested?

Either the mind-control skateboard that went 50kmph or the robotic goalkeeper. That was fixed in the middle and there’s a grid, so it instantly measures where the ball is going and gets the goalkeeper in the right position. There are videos online of Messi having a go against it and, at top speed, he couldn’t get a ball past the robot.

And the most pointless?

This toothbrush – can’t remember the brand – that sent details to your dentist to say you had been brushing your teeth for two minutes. But it didn’t actually measure anything: it didn’t tell you the quadrant, you could fake it, and why would your dentist want to have this data? Basically it told you two minutes had passed and that you’d said you’d brushed your teeth. No idea what that was about.

Next up is a one-off memory competition for teenagers on Watch called Memory Slam. Do you use any of the techniques now yourself?

Yeah, I’ve started trying to do it on Countdown with names, because so many contestants come through. We have at least six a day so I’m just trying to imagine them in weird situations doing weird things! That’s the thing: it’s all about building mental images and the weirder the images the better. But you do remember things; they do stick in your mind for a lot longer.

To find out more about the Astellas Innovation Challenge visit: astellas.eu/innovation-challenge. Enter by 24 October.