On average, there are as many prime numbers for which the sum of decimal digits is even as prime numbers for which it is odd. This hypothesis, first made in 1968, has recently been proven by ...

To calculate the sum-of-the-years' digits, you add up each of the years of an asset's useful life. So for example, if an asset had a useful life of six years, you would add up 6 + 5 + 4 + 3 + 2 ...