compared the decimals 66.10, 21.10, and 66.11. which is greater

In order to compare decimals with each other, we first have to compare the left side of the comma which is the whole number and then if the left side is equal, we go to the right side of the comma which is the decimal. In our case we have these three numbers: 66.10, 21.10, 66.11.

If we compare the left side of the commas we will have: 66, 21, 66. So we already know that 21.10 is not the greatest number. Since we have two 66s, we will start to compare the right side of the comma. We compare every digit starting from the one closest to the comma. We stop when the digits are not the same and we compare them both. The biggest number is the one with the biggest digit.

We have 66.10 and 66.11. The first digit after the comma on both of them is 1, so we need to go on the second digit after the comma.

On 66.10 the second digit is 0 while on the 66.11 the second digit is 1. 

If we compare both of them, we will have 0 < 1 so that means that 66.10 < 66.11.

66.11 is the greatest number.