Would the opposite of 10 be -10 or 0.10?

-10

It depends which “opposite” you mean

The additive inverse of 10 is -10

The multiplicative inverse of 10 is .10

I just ask because we were discussing the concept of the smallest number.... even though there is no "smallest" number because you can also go smaller, BUT if there was a concept of one.... someone said it would be 0.000000000000000000000000000000000000000000......... with an infinite number of 0s eventually being followed by a 1 being at the "end". But I was saying it would be an infinitely small negative number.