Legal department managers routinely face challenges due to human beings’ seemingly built-in cognitive limits on how well they deal with some numerical aspects.

Consider big numbers. Unless well-trained or possessed of an individual proclivity, most of us can’t grasp the extent of 10,000 documents very well let alone $10 million of legal fees. For example, 1 billion $1 dollar bills stacked up would be 47 miles high, but that doesn’t really help us.

Homo sapiens just don’t seem equipped with brains that have evolved to cope with numbers in the thousands, let alone many times bigger. Probably most of us toss around such large numbers—GDPs in the trillions, revenues in the billions, settlements in the hundreds of millions, law firm fees in the millions—yet deep down we aren’t comfortable with the magnitude of numbers at those scales. We cope but we don’t intuitively grasp them.

Nor are we adept at appreciating the implied level of accuracy of numbers. The expectation is that a number’s accuracy is given by its last non-zero digit starting from the right. For instance, 5,400 is plus or minus about 100; 3,500,000 could be off by 100,000, but an inside legal budget of $3,502,989 had better be spot on.

It means that benchmarks that say 54.6% of all general counsel believe thus and so are probably exaggerating their precision. We tend to take many numbers on faith and not subject them to commonsense scrutiny.

Ponder for a moment a third mental wall many can’t climb over. Why do lawyers of all stripes find averages easier to deal with than more reliable medians, even though very large or very small outliers throw off the representativeness of averages?

It just seems easier to grasp the result when you add a bunch of figures and divide by how many there are (the average) than to sort them from high to low and pick the number half way down from the top (the median). We just aren’t hardwired with that facility.

And pity the in-house staffer who confronts standard deviations. It more than confuses people to think of subtracting lots of numbers from the average of all of them and then squaring that result before finding the square root (square root, as in root canal?). So too do ratios, such as dollars of revenue per legal staff, give us pause … or cold sweats. Ratios don’t readily translate into graspable, useful metrics for some people.

My point is that hardwired functions in our brains have not evolved to where we feel at home with some kinds of numbers—very large numbers, estimates of numbers, dispersions of numbers and roots of numbers. Those who produce metrics have a special burden to translate their findings in ways that our sometimes ill-suited brains can wrap around.