Counting coins: add them up here or print

The four coins

• A penny is 1 cent, written 1¢. It is drawn in a copper color; the other three are grey.
• A nickel is 5 cents. It is bigger than a penny and bigger than a dime.
• A dime is 10 cents. It is the smallest of the four, though it is worth more than a penny or a nickel.
• A quarter is 25 cents, a quarter of a dollar. It is the biggest of the four.
• 100 cents make a dollar. Amounts under a dollar are written here with the cent sign, like 35¢. From a dollar up they are written with the dollar sign, so 135 cents is $1.35.
• One way to count: start with the coins worth the most and count on. For 2 quarters, 1 dime and 3 pennies: 25, 50, 60, 61, 62, 63. That is 63¢. The pictures put the coins worth the most first.

The three kinds of sheet

• Pennies, nickels and dimes: 2 to 6 coins in a picture, up to 60¢.
• With quarters: 3 to 6 coins, at least one of them a quarter, from 27¢ to 99¢.
• A dollar or more: 5 to 9 coins, at least three of them quarters, from $1.00 to $2.25.
• The sheet number: any whole number from 1 to 999999. The same coins and sheet number make the same twelve pictures on any device, so a whole class can have the same sheet, and no two pictures on a sheet add up to the same amount. If we change how the page picks coins, a sheet number will make a different sheet.
• The wrong answers on the screen come from slips like these: every coin counted as 1 cent, the dimes and the nickels the wrong way round, or one coin too many or too few.
• How big they print: on a Letter sheet, each of 6 or 9 pictures sits in a square about 6 cm wide, and each of 12 pictures in a square about 4 cm wide. A quarter then prints a little under 2 cm wide, or a little over 1 cm with 12 to a sheet. Both are smaller than a real quarter.

Every time the page is built, a program makes 1,200 sheets (400 of each kind) and counts all 14,400 pictures back from their drawings, with code written apart from the page’s own: it counts the circles of each coin, checks the size of each one and the value written on it, that no two coins touch, and that 25 for each quarter, 10 for each dime, 5 for each nickel and 1 for each penny add up to the amount on the answer sheet. It does the same for every mix of up to nine coins the page could draw, all 714 of them, checks that the four answers on the screen are four different amounts with the right one among them, and measures the 6 ways the page can lay pictures out on a sheet.

What this page does not do

• It has U.S. coins only, and only these four: no half dollars, no dollar coins and no bills. To add up real bills and coins there is Count the cash.
• It does not show real coins. Each coin is a plain circle with its value on it, so there is no practice here at telling coins apart by their faces. The sizes are in the same order as real coins, and they print smaller.
• It does not make change, and it does not compare prices or work out what you can buy. Count the cash, above, counts back change.
• It does not check coins you draw. Nearly every amount can be made in more than one way. The answer sheet shows one way, and it may not be the one with the fewest coins. On the screen there are only pictures to count.
• It does not keep score after you close or reload the page, or pick another sheet. The sheet number brings back the pictures, not your answers.
• It is not a lesson plan and follows no school’s program or grade. It makes no promise about what anyone will know after using it. It is pictures to practice on.
• It cannot be read from the picture by a screen reader. “What is in the picture?” says in words how many of each coin there are. The page has not been tried with a screen reader.
• It cannot see your printer. On a black-and-white printer the pennies come out grey like the others, and the value on each coin tells them apart. It has been tried in one browser’s print preview (Chromium, saved as PDF), where each sheet came out on one page; it has not been tried on paper from a real printer.