Calculating four times 0.9

To calculate four times 0.9, you begin with the number represented by 0.9 and multiply it by 4. Multiplying by 4 means you are essentially adding 0.9 to itself four times, combining it repeatedly to reach the total. Using the expression (0.9 * 4) clearly shows this multiplication step. Here, 0.9 is your starting number, and multiplying it by 4 yields the value 3.6. Understanding this process helps to grasp how multiplying any number by 4 increases its value exactly fourfold, which is the essence of calculating four times 0.9.