New Super Mario Bros. - How to unlock world 4 and 7

This is how you unlock world 4 and 7. You play the castle of level 2, but you have to be mini, like not just small, mini Mario/Luigi. Then you have to beat the level as a mini dude, then it unlocks the world, for world 7 you play world 6's castle, to unlock one half of it, then play world 8's castle which unlocks the other half of world 7. That's how

Cool, but I don't play that game

dude thats easy i beat this game like 15 times plus that mqario kart thing is a lie he modded his DS Lite

who?

the guy on Youtube with the MarioKart in SuperMarioBros.

Oh. have no idea.

Neither do I.

that'd be cool though.