Figure 2: Five-year-old children’s performance on approximate addition, subtraction and comparison problems. What processes underlie children’s symbolic approximate arithmetic? We first considered ...

Before the 13th century Europeans used Roman numerals to do arithmetic. Leonardo of Pisa, better known today as Fibonacci, is largely responsible for the adoption of the Hindu–Arabic numeral system in ...

Randolph Grace receives funding from the Marsden Fund, administered by the Royal Society of New Zealand. Everyone knows that arithmetic is true: 2 + 2 = 4. But surprisingly, we don’t know why it’s ...

Consider this sequence of numbers: 5, 7, 9. Can you spot the pattern? Here’s another with the same pattern: 15, 19, 23. One more: 232, 235, 238. “Three equally spaced things,” says Raghu Meka, a ...

You may never have heard of modular arithmetic, but you use it every day without the slightest difficulty. In this system, numbers wrap around when they reach a certain size called the modulus; it is ...