why does unity never get highest number in random.range code example

Example 1: random.range unity

// returns 0 - 9
Random.Range(0, 10)

Example 2: unity random range

Random.Range(-10.0f, 10.0f);

Example 3: unity random range int not working

float rand = UnityEngine.Random.Range(0, 4);              Debug.Log(rand);