Most children his age may draw pictures on paper with crayons, but nine-year-old Lim Ding Wen has a very different canvas.

The primary school student from Singapore writes applications for Apple’s iPhone, and his latest project, a painting program called Doodle Kids, has been downloaded over 4,000 times from Apple’s iTunes store in just two week. He states he derives inspiration by creating programs for his sisters, ages 3 and 5, to doodle with.

This whiz-kid has actually completed 20 different programs in 6 different programming languages (including Javascript and ActionScript), which for a 9-year old is impressive enough. He started on a computer at age 2, and by 7 was actively programming on one.

The apple doesn’t fall far from the tree: his father also works for a tech company writing iPhone applications, and father and son compete to see who has more downloads of their respective apps.

Lim is currently writing another iPhone app – a space race game called Invader Wars.