How many periods does 8 digits have?

Answer 1

One. As in "12 345 678." This is an 8-digit number ~ 12 million...

Rather than commas, a space between groups of 3 is often preferred because the comma is sometimes used to indicate a decimal point.

The "period" or decimal point following the 8 can be omitted unless decimals are included, as in writing dollars & cents: $12 345 678.00

The French version would be 12 345 678,00$