Attic numerals are ancient numbers that were used a long, long time ago in Greece to count things. Imagine you are playing with your toys and you want to know how many of them you have. You could count them all up by saying "one, two, three, four". Well, ancient Greeks had their own way of counting things using attic numerals.
These numerals are very special, they look like little pictures! There is a symbol for "one" that looks like a line, and then a symbol for "two" that looks like a V shape. The symbol for "three" looks like an upside-down V, and the symbol for "four" combines two of the V shapes together.
As you can imagine, these symbols can get pretty tricky when counting bigger numbers. So, the Greeks came up with a special way to make things easier by adding up the symbols in groups of five or ten. For example, if you count up to five using the line symbol, you can start again with a new line and put a diagonal line over it to show it's the second group of five.
Overall, attic numerals were a clever way for ancient Greeks to keep track of things and count their belongings. Today we use the more familiar Arabic numerals that use 0-9, but it's still fun to see how people used to count in different ways a long time ago.