# Janitor Math

Quote of the Day

To achieve great things, two things are needed; a plan, and not quite enough time.

— Leonard Bernstein. Similarly, Duke Ellington used to say "I don't need time – I need a deadline."

Figure 1: Typical Janitorial Paper Products.

I was working on a Saturday morning when the cleaning crew came in. On this morning, the owner of the cleaning company was with his crew. He stopped by my cube and wanted to speak for a few minutes about some cleaning issues he was seeing. His concerns centered on their increase in workload caused by a recent in the number of workers at our site.

He began the conversation with a statement something like:

You have added quite a few people lately. You have doubled the number of women and increased the number of men by about 10.

We have added a number of people lately, and I was surprised how accurately he knew the numbers. I was a bit curious about how he knew our staffing level and asked him how he figured the numbers of men and women out.

He told me that the number of paper products used by men and women in the bathroom makes the number of people in the building very predictable. He said that every six people using a bathroom means one extra carton of paper towels each month. Additionally, the usage rates of the different types of products vary between men and women. Thus, he was able to accurately estimate how many men and how many women we have added recently. He even told me where the engineers were from based on their toilet seat cover usage. I must admit, I was impressed.

Sometimes, these "rule of thumb" estimates can be uncannily accurate. For example, I once saw a government contract official get wide-eyed when a senior engineer determined a classified number by just making a few routine observations of unclassified information. Of course, he was not supposed to know that number, but a little math and physics gave it to him. This sort of thing happens all the time in the defense business. They even have a name for it – classification of compilations.

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