None of the numbers are underlined.
In the number 56123, the 5 has a value of 50000, the 6 has a value of 6000, the 1 has a value of 100, the 2 has a value of 20 and the 3 has a value of 3.
23
33
23 x 56 = 1288
23 as a percentage of 56 is: 23/56 times 100 = 41.07% to two decimal places
A decimal number is simply a way of representing a number in such a way that the place value of each digit is ten times that of the digit to its right. A decimal representation does not require a decimal point. So the required decimal representation is 56, exactly as in the question.
56 x 23 = 1288
Sadly, it is not. 56 is 143.5% more than 23.
23/56 cannot be reduced further.
23 goes into 56 2 times
56 = 23 × 7
23 + 56 - 4 = 75