Arithmetic

Names of Small Numbers: One to Twenty

Having looked at words for large numbers, let’s turn to the less-asked, but still interesting, question of where our words (in English) for ordinary little numbers come from. We’ll look at the origins of one, two, three, then eleven, twelve, thirteen, and then first, second, third.

Names of Large Numbers: Vigintillion and Beyond

Last time we looked at names of anniversaries (like “semiquincentennial” for the 250th), and other words based on Latin numbers (like “septuplets” for 7 babies). Let’s back up and look at the names in English for large numbers themselves, like million, trillion, and vigintillion. We’ll work up to the big ones!

What is a Semiquincentennial?

This is the 250th anniversary of the United States, and as a result we’ve heard the term “semiquincentennial” a lot. (Well, a lot more than usual.) That reminded me of several past questions about such terms, so we’ll take a look at them now, starting (after a quick introduction) with one asked 25 years ago …

What is a Semiquincentennial? Read More »

Three HCF/LCM Problems

Let’s look at three similar questions we’ve received about Least Common Multiples, Greatest Common Factors, and so on, starting with a recent question and going back in time. We’ll see a bad question, a good question, and an interesting challenge.

When Percentages Don’t Make Sense

Last week’s question led to a number of previous questions, which would have made it too long. Here we’ll look at the last couple references we gave, dealing with percentages of a negative base. This time, the problems will be mostly about money.

Percentage Change in Temperature?

Continuing to look at past questions that didn’t make it into the blog, I find a question about percentage change in temperature, which nicely ties together a couple older topics that have long been on my list to cover. Let’s do that now.

Dividing Decimals: How and Why

We have looked at how we add, subtract, and multiply decimals. Now we’ll conclude with division: what we do, why we do it, and how we don’t really need to do it that way.

Multiplying Decimals: How and Why

We’ve looked at how to add or subtract decimals. Now let’s move on to multiplication; we’ll look at three answers to the same sort of question.