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A couple of weeks ago, signs like this one appeared in dining halls across the Queens College campus:


At the time, the price of a bottle of soda was $1.50. Note the amount of the increase stated on the sign, as quoted above: 0.7¢. As is (hopefully) still taught in homes and elementary schools across the country, one cent, which can be written in figures as 1¢ or $0.01, is a hundredth part (1/100) of one dollar. Also (hopefully) taught in elementary schools is the concept of real values between zero and one – “Fractions.” Young students also (hopefully) learn about a concept called “place value,” which essentially means that for each digit to the left or right of the decimal point, the digit’s value increases or decreases by a factor of 10. Therefore that 0.7¢ increase reported on these signs means that the increase is less than one cent (7×10^-1 < 0×10⁰). If anyone remembers that sketch from Square One TV, that dealt with the different ways of expressing fractions (which first aired in 1987), 0.7 could also be written as 70% and 7/10. (I should note that they write and say the decimal form of the fraction without the leading zero, but its value is the same.) If you don’t, I miraculously found it on YouTube. Watch and learn.



Why am I going on and on about the value of “zero point 7 cents”? Well, when I first saw this sign, I thought that it was interesting that they would increase the price by seven-tenths of a cent, bringing the price to $1.507 (or more sensibly, rounding up to the nearest cent, $1.51). On November 30th, they increased the price, but instead of seven-tenths of a cent, the price increased by seven cents! The amount of the increase was ten times the amount reported on the signs!

This is just a part of a disturbing trend that I’ve seen across the region, where people seem to be forgetting about place value, and how it relates to dollars and cents. If I were to go to a store which displays a sign advertising copies at a price of “.10¢” I would easily expect to walk in, make ten copies of something, and pay exactly one cent, because the sign advertises copies at one-tenth of a cent. However, if I am asked to pay a dollar, I would protest, saying that the sign says “.10¢,” and that “.10¢” is less than one cent, and 10×.10¢ is 1.00¢.

My point: If you’re going to raise the price of something by seven cents, just say that you’re raising the price by seven cents, not a fraction of a cent. Besides, I don’t think I have enough coupons with statements of cash value being a fraction of a cent to make seven-tenths of a cent!