Do you know how many zeros there are in a duotrigintillion? Or which country has the greatest number of smartphones? Have you ever heard of the 'curiosity gap'? And do you know how fast the speediest passenger zooms over the tracks? Discover the answers to all these and much, more more in Big Countdown: Technology.

The Big Countdown looks at popular topics and investigates the great many numbers that make them fascinating. From the mind-bogglingly large to smallest and most precious, this series helps us understand that it's not just our days that are numbered. Ideal reading for number-crunchers aged 9 and up.