The language user as an arithmetician

Dutch, like other languages, has approximative expressions with two numerals, for example: "twee, drie boeken" (lit. two, three books; two or three books). This construction is analysed. It turns out that the choice of number words is not arbitrary. Various kinds of factor are involved, as is shown using language materials from large corpora of Dutch texts. The interval between the two numbers has to be 1, 2, 2 1/2 or 5, multiplied by 10n, at least in the decimal number system. It is argued that in daily life this set of so-called "favourite numbers" has a special role. Coins and banknotes, prices of special offers, bidding conventions in auctions are based on, or make use of, this set of numbers. An explanation for this favouritism is offered in the framework of the triple-code model of human number processing proposed by Dehaene. The explanation substantiates Dehaene's claim of the existence of an analogue magnitude code used in estimating and comparing. Human cognition seems to be able to perform simple calculations with quantities (e.g., halving and doubling), independently of any counting or number system.