Post #3037348

A novelty item: the Prime Number Ruler (素数ものさし) can measure up to 17cm in the centimeter increments. For example, 8cm will be measured between the 5 and 13 markings. However, there are integers that cannot be derived from the subtraction of two prime numbers (e.g. 25, 33, and many others). #mathematics #math #数学 #PrimeNumbers #素数