To arrange the numbers 12, 56, 27, and 42 from least to greatest, we start by comparing each number.
First, we identify the smallest number, which is 12. Next, we look at the remaining numbers: 27, 42, and 56. Among these, 27 is the smallest, followed by 42, and then 56, which is the largest.
So, the order from least to greatest is:
12, 27, 42, 56