It would take a very long time to count to 7 billion by counting one number at a time. To give you an idea of how long it would take, if you were able to count one number per second, it would take you about 220 years to count to 7 billion. However, this is just a rough estimate and the actual time it would take could be longer or shorter depending on various factors such as how quickly you are able to count and any breaks you might take.