The underlying concept applied here is the place values. Each digit of a number holds its own value. The digit increases in value by 10 as it goes from the rightmost to the leftmost digit. Take for example, the number is 111. It contains the same digit of 1. But the ones digit has a value of 1, the tens value has a value of 10, and the hundreds digit has a value of 100. Hence, as you go from the lesser-value digit to the greater-value digit, the value increases by 10.
