for this achievment just type in these
To unlock the various features and items below, insert the corresponding code at the university’s math classroom.
* Artifact Detector - VIKED7
* Beep Beep - VNF59Q
* Character Treasure - VIES2R
* Disarm Enemies - VKRNS9
* Disguises - 4ID1N6
* Fast Build - V83SLO
* Fast Dig - 378RS6
* Fast Fix - FJ59WS
* Fertilizer - B1GW1F
* Ice Rink - 33GM7J
* Invincibility - B83EA1
* Parcel Detector - VUT673
* Poo Treasure - WWQ1SA
* Regenerate Hearts - MDLP69
* Secret Characters - 3X44AA
* Silhouettes - 3HE85H
* Super Scream - VN3R7S
* Super Slap - 0P1TA5
* Treasure x2 - VM4TS9
* Treasure x4 - VLWEN3
* Treasure x6 - V84RYS
* Treasure x8 - A72E1M
* Treasure x10 - VI3PS8
* Treasure Magnet - H86LA2
and it still unlocks the achievmnet