полуторамиллионный клиент

[azu]

1,5 millionth customer

или не пытаться передать патетику и просто написать:

In 2008 the number of the Company's customers reached 1,5 million.

[%&$]

consider:
1.5 Million Customer Milestone

[azu]

А если в предложении - In 2008 the Company reached/passed/hit? 1.5 million customer milestone?

[%&$]

Agreed:
In 2008 the Company crossed/hit/reached the 1.5 million customer mark/milestone/target

[azu]

Thanks!