I'm gonna go for it. / I'm gonna give it a try. / I'm gonna give it a go.

Can you spell it out for me? / Can you explain it in detail for me?

Search me! / I don't know. / I don't care.

62.2kg

What we might end up doing is combining options 1 and 2.

Jeez, you scared me! / Jeez, I didn't see you there! / Jeez, where did you come from?