I see lots of bloggers out of the desire to increase their CRT, disobey google TOS by placing more than the specified Google Adsense Unit per page specified by Google. Lots of account get banned or suspended by google just because the publisher never read through their terms of service while. If you desire to know how many adsense units are allowed on a page, then this post is for you.
Google Adsense For Content – Three adsense units are the maximum required for Adsense for content.
Adsense for search – Two search forms are the maximum you should use per page.
Adsense for mobile – One adsense unit for mobile unit is allowed on a mobile wap page. Though there are two types of adsense for mobile units viz; Single and Double unit. The double unit is to place placed at the bottom while the single unit can be placed whereever you wish.
Anything outside this is against google TOS.
Hope this helps.