Evil number
= Evil number
{wiki=Evil_number}
An **Evil number** is a non-negative integer that has an even number of 1s in its binary representation. For example, the decimal number 3, which is represented in binary as \`11\`, has two 1s, thus making it an Evil number. In contrast, the number 5, which has a binary representation of \`101\`, has three 1s and is therefore not an Evil number.