Can you say half a millionth instead of one ten-millionth?

Question

I'm in a disagreement with someone about a math term.

Instead of saying one ten-millionth, is saying half of one-millionth valid?

Not just valid in conversation, but truely valid, as in you could publish a paper with that term.

Answer 1

1/2 of a millionth is 5 ten millionths, not 1 ten millionth: .5 x 10^-6 = 5 x 10^-7 ≠ 10^-7