sqrt(49) = 7
So this number is in the set of...
- Natural numbers
- Whole numbers
- Integers
- Rational numbers
- Real numbers
The set of natural numbers is {1,2,3,...} and the set of whole numbers is {0,1,2,3,...}. Basically we just added in 0. Integers will be similar but we now have negative values too {..., -3, -2, -1, 0, 1, 2, 3, ...}
Rational numbers are anything of the form a/b with a,b being integers. In other words, if we can write the number as a fraction of two integers, then we have a rational number. In the case of 7, we have 7 = 7/1, so it is rational.
The set of real numbers includes every number type you have learned of so far (natural, whole, integer, etc). If you haven't learned about imaginary or complex numbers yet, then every number your teacher will go over is a real number.