How many zeros are in 10 bilion?

Answer 1

In American usage:

1 billion = 1 000 000 000
10 billion = 10 000 000 000

10 zeros.

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In traditional British usage and in many other parts of the world:

1 billion = 1 000 000 000 000

10 billion = 10 000 000 000 000

13 zeroes.