# What Numbers Should You Remember?

The United States is currently home to 327 million people, which is about 4% of the 7.7 billion people on earth. I find it extremely helpful to memorize these three numbers as I read any other statistic. One fluid ounce is just under 30 ml, and if I could remember that, I would find it useful at the grocery store. So, what other numbers do you need to memorize for everyday life?

### Statistics

Knowing general statistics will help you contextualize other statistics. 40 million Americans live below the poverty line, and if you know the population of the United States, you know that it is more than 1 in 10 people. If you hear that 0.6% of Americans identify as transgender, that means about 2 million people.

The national and global population changes slowly and steadily enough that you only need to update your mental model every few years. Some of the statistics are a little more complex: it’s good to know that the dollar’s annual inflation rate has hovered between 0.7% and 3.0% over the past ten years. So, depending on the year, a high-yield savings account can make or lose money.

Another favorite metric of mine: Currently, the average height in the United States is 5’4 ” for women and 5’9 ” for men. So I’m actually NOT THAT SHORT.

### Conversions

It’s good to know that a mile is about 1.6 km and the city speed limit of 50 km / h is 31 mph. A very crude conversion is that each mile is about a kilometer and a half, and each kilometer is about two-thirds of a mile.

A gram weighs 0.035 ounce, while an ounce, on the contrary, weighs about 28 grams. Comparing weights in two systems is a headache, but memorizing the numbers will help you in very rough comparisons.

Pounds and kilograms are much simpler: a kilogram is roughly 2.2 pounds, so if you have to count 10, 20, or 30 kg, that’s 22, 44, or 66 pounds.

### ETC.

There are tons of specific numbers to remember: if you load a 45-pound cymbal on either side of a 45-pound bar, it will be 135 pounds; two plates on each side – 225 lbs. People speak 125-150 words per minute. The standard floor of the building is 10 feet high. Every five seconds between a flash of lightning and a bolt of thunder, you are one mile away from that lightning.

And of course, you should always remember a few personal numbers, such as your contact’s phone number, your hourly pay, and your basic health statistics.

What numbers do you remember and how did they help you? Points for the most unexpected answers.

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