1 Jamie: Poor Adam! Choking on a giant frog. If only there was some way to put him out of his misery.
1 Adam: <hack> <choke>
2 Jamie: Well, despite the fact that we're already dead.
2 Adam: <cough> <splutter>
3 Jamie: What's that, Adam? Look behind me?
4 Jamie: 38 tons of dynamite? Now where did that come from?

Of course Jamie can tell exactly how much of it there is just by looking at it. It's dynamite - he has a lot of experience!

I considered using the metric tonne spelling, as would be customary for me in normal usage, but I decided the difference wasn't really important in this case, and didn't want to bother with a spelling that might be unfamiliar to some readers when the alternative, ton, is still used even in metric countries.

As is usual with quaint antiquated units of measurement, there are approximately 30 different and mutually contradictory definitions of how much a "ton" is. Thankfully, they're all reasonably close to one another. And when it comes to dynamite, a few percent difference won't really be terribly important.