yes
Yes.
yes
It must be a generalised rational number. Otherwise, if you select a rational number to multiply, then you will only prove it for that number.
Yes. Any rational number divided by another rational number is also rational.
There's only one number that equals 640. The number is . . . . . 640.
It is a rational number. It can be written as a fraction.
640
yes
27 x 5 = 640
Is 12.05 a rational number or irrational number?
1.96 is a rational number
It is a rational number, as it can be written as a fraction.
Yes, the sum is always rational.
There is no such thing as a number that is both rational and irrational. By definition, every number is either rational or irrational.
As much as, in these days of uncertainty, anything can be anything. As long as the constraints of a rational number are kept to, a rational number will always remain a rational number.
Yes, it is.