JMulder on Family Tree Circles

I?ve been transcribing letters for one of my ancestors: Lodewijk Wesselo. In almost every letter he writes about his business. But he doesn't write out the numbers of the profits he makes, instead he uses some sort of code. It's not Roman numbers and it's not just a letter for number substitution (like a=1, b=2). I am hoping some of you might have an idea about this code and how to crack it?

Some background: Lodewijk is manager of a store for jewelry, and objects of gold, silver and other precious metals. The profits are quite high, one number he does write out in normal numbers is in his letter from 15 March 1925, where he says: "No business news, today I've already passed 25 thousand." The only other time is in the piece below.

The bit where he's written his profits in code is in a letter dated 7 March 1925:

"Nevertheless, sales are good. Februari ? iij,- and in total these first two months ? ijnhh,- higher than in '24. This week is especially good. I sold stuff for 6 thousand over the counter and on order 3 necklaces and 5 tie pins, total ? ihnhh,-."

A little later, he says:

"This afternoon, I was in Den Haag for business, where I had the last laugh. Their turnover last week was ? ouhh,- and mine was ? zehh,-."