You're not the only one whose mind is boggling over the square root of Pi this weekend as from the looks of Katy Perry, she's got homework on her mind too after she headed on a night out in London in a very preppy outfit last night. Channelling a bit of Cher from Clueless, she was working over the knee socks with a very 90s inspired checked skirt and fluffy tee.

Katy Perry heads on a night out in London to Nobu. Katy Perry images -

Having touched down in the UK ahead of her closing night performance at this year's iTunes Festival, Katy headed out for a bite to eat with a few pals. Heading to fancy restaurant Nobu, she was rocking a 90s vibe in head to toe preppy gear.

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Going for a monochromatic feel, she kept her colours simple in black and white, but totally mixed up the patterns and textures in a diamond print mini and mohair t-shirt. Adding over the knee socks and a big ass bow in her dar black locks, she added a black leather backpack, brogues and a matching coat.

Make up wise, she went for a touch of the vixen - pairing a pale face and strong brows with a big slick of red lippy.

Katy Perry heads on a night out in London to Nobu. Katy Perry images -

We're not sure we could pull off everything that's going on in this one ourselves, but we are actually kinda loving it on K-Pezza.

But whadda ya reckon? Is it a fashion hit or a massive miss?

Comments please...

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What do you think?