Asked wrong?

Terri,

The question and its answer are correct.

As it is specified that it is a number written in the French/European system, the ‘ virgule/ (decimal comma) ‘ is used to separate the ‘ whole number’ from the ‘ decimal  fraction ‘.   Hence the ‘ translation ‘ into the English/Imperial numerical system as ‘ 78.005 ‘ ( 78 decimal point 005 ).

It is an important  point of the lesson that this significant difference exists between widespread European usage, and English-speaking countries in particular. 

 The ‘ virgule ‘ is never used in the ‘French’ system to separate hundreds from thousands, thousands from millions, millions from billions etc etc. In the French system these separations are usually just a clear space,  but unfortunately sometimes a ‘ . ‘  leading to even more potential confusion to be aware of ! 

From the 3rd link below 

           “ Great Britain and the United States are two of the few places in the world that use a period to indicate the decimal place. Many other countries use a comma instead. The decimal separator is also called the radix character. Likewise, while the U.K. and U.S. use a comma to separate groups of thousands, many other countries use a period instead, and some countries separate thousands groups with a thin space. Table 1-3 shows some commonly used numeric formats. “ 

See links for more discussion on the significant differences  :

https://quicksilvertranslate.com/252/numbers-decimal-comma-or-decimal-point2/#:~:text=The%20short%20answer%20is%2C%20English,exceptions%2C%20such%20as%20Mexican%20Spanish. 

https://www.smartick.com/blog/other-contents/curiosities/decimal-separators/

 https://docs.oracle.com/cd/E19455-01/806-0169/overview-9/index.html

I must have missed something in math because I still don’t get it.

Terri, 

try some other equivalent numbers

A) French/European system 78,5 

is the same number as

   English/American system 78.5 

B) French/European system 78,05   

 is the same number as

   English/American system 78.05 

C ) French/ European 78,005   

 is the same number as

    English/American 78.005 

D) French/European 78,0005    

is the same number as

    English/American 78.0005

We don’t use decimal points in English we use commas. The only place we would use a decimal point is if it was something like 78,005.00. The French use decimal points or a space 78.005 or 78 005. When I go into the explanation on Kwiziq that is how they explain it as well so I think the question they are asking is backwards. It should read “This number written in English: 78,005” how would that be written in French? Which would be 78.005 or 78 005

Terri, 

The number in the question written in the French system is not the number ‘ seventy-eight thousand ( and ) five ‘.

 It is the number 78 followed by the fraction 5/1000 in decimal form - which is therefore written as 78,005 in the French system.

How do you write the number 78 followed by 5/1000 in decimal form in your part of the world ? 

Do you use 

a ‘ decimal comma ‘  between ‘ 78 ‘ and ‘ 005 ‘ giving ‘ 78,005 ‘ - as per the French system, 

or 

a ‘ decimal point ‘ between the ‘ 78 ‘ and the ‘ 005 ‘ - giving ‘ 78.005 ‘ - as per the English system ? 

This is not really a French grammar issue - it is an international notation issue. 

The French system never uses a ‘ decimal point ‘, only a ‘ decimal comma/virgule ‘, so anytime you see the virgule/comma in a French written number, it needs to be replaced by a  ‘ decimal point ‘ if you want to interpret/rewrite the number using the English system. 

It is worth reading the links I added previously , or search for others which discuss this and the other differences in detail. 

For example :

 https://www.numeracyteachersacademy.com/blog/tocommaornottocomma#:~:text=In%202003%2C%20at%20the%2022nd,300%20million%20456%20thousand%20207

Just to sum this actually simple matter up:

(French:) 78.005 --> 78-thousand-and-five --> (English:) 78,005
(French:) 78,005 --> 78-decimal-005 --> (English:) 78.005