yes
Yes.
Always, unless the original number is zero. This does not have an inverse.
The answer will depend on what you mean by "opposite": the additive inverse or the multiplicative inverse.
An inverse, without any qualification, is taken to be the multiplicative inverse. is The inverse of a number, x (x not 0), is 1 divided by x. Any number multiplied by its inverse must be equal to 1. There is also an additive inverse. For any number y, the additive inverse is -y. And the sum of the two must always be 0.
The additive inverse of EVERY positive rational number is a negative number.
No. The additive inverse of zero or a negative rational number is not negative.
yes
Zero.
Zero.
Yes.
The number is 7.
Zero.
The rational numbers form an algebraic structure with respect to addition and this structure is called a group. And it is the property of a group that every element in it has an additive inverse.
Yes, almost half of them have additive inverses which are negative.
The answer depends on whether the "opposite" means the multiplicative inverse or the additive inverse.
The additive inverse of 18 is -18. The additive inverse of any number is the opposite of that number, such that the sum of the original number and the additive inverse is zero.