Khan/khan-exercises — Issue #13229: Subtraction 4 - scratch pad 
Author: KhanBugz
Created: 2012-02-07 04:08:03+00:00
State: open
Labels: chrome, other, vista

the first time I use it,it works fine. the second and third time, only half of it works and it only has black.

[subtraction_4.html?seed=146&problem=0](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/subtraction_4.html?seed=146&problem=0&debug)

[Answer timeline](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/subtraction_4.html?seed=146&problem=0&debug&activity=%5B%5B%22incorrect-activity%22%2C%22%5C%224749%5C%22%22%2C29%5D%5D)

["4749"]

Mozilla/5.0 (Windows NT 6.0) AppleWebKit/535.7 (KHTML, like Gecko) Chrome/16.0.912.77 Safari/535.7

MathJax is loaded, ready, queue length: 0