The numbers when first shown in the grid change colour when displayed in the houses. This allows your number to found as it provides more information to the 'other end' than you think.
Come on, dude... did that really amaze you?! It's lame!! You choose a number, than "say" it's color... there are 4 numbers with that colour... when you get to the part with the houses, each of this 4 numbers is in a different house, u click the house and WOW, he's got u'r number... I mean... come on!