[theamk]

If you want to be unambiguously understood, especially in international context, it seems it's better to avoid words beyond "million" altogether.

"million of millions of dollars" or "ten to the twelfth dollars" or "one tera dollar" or even "one EEE twelve" (for programmers) will always be understood correctly, no matter which part of world listeners are from.

[qsort]

The only everyday context where numbers on that scale are commonly used is money/finance, and it's pretty universal in that context that 1e9=B=billion, 1e12=T=trillion. This long scale/short scale distinction gets posted a lot but it's one of those cases where in practice it seems to matter very little.

In science and engineering you'd rather use scientific notation anyway, and in math and CS notoriously only 3 numbers exist: 0, 1 and n.

[semanticc]

You don't seem to get the point. That is only universal in current day English. In e.g. Finnish: miljoona = 1e6, miljardi = 1e9, biljoona = 1e12, triljoona = 1e18.