Children with ADHD (attention deficit hyperactivity disorder) can be hyperactive which can make it difficult to get to sleep. Bedtime can also be chaotic and stressful for parents.
Rational Numbers 5/1, 1/2, 1.75, -97/3 ... A rational number is any number that can be written as a ratio of two integers (hence the name!). In other words, a number is rational if we can write it as a fraction where the numerator and denominator are both integers.
The number two has many properties in mathematics. An integer is called even if it is divisible by 2. For integers written in a numeral system based on an even number, such as decimal and hexadecimal, divisibility by 2 is easily tested by merely looking at the last digit. If it is even, then the whole number is even. In particular, when written in the decimal system, all multiples of 2 will end in 0, 2, 4, 6, or 8.