What is the word guadrillion mean?

There are actually two different meanings for "quadrillion," depending on where you are in the world:

* Short scale (US, UK, Canada, Australia): A quadrillion is 1,000,000,000,000,000 (1 followed by 15 zeros). This is equal to 10^15.

* Long scale (most of Europe, Latin America, and some other regions): A quadrillion is 1,000,000,000,000,000,000,000 (1 followed by 24 zeros). This is equal to 10^24.

So, it's important to clarify which scale is being used when discussing a quadrillion.