They are: 8.10 and 8.100
81 is a whole number whose simplest form is 81.
0.81
It is already rounded to 2 decimal places since there are no decimals in this number.
81/10
The simplest way is to write is as 2.025, as a fraction in decimal form rather than in the form of a ratio. That does not stop it being a fraction and, being a decimal, there is no simpler form. Its rational equivalent is 2025/1000 which can be simplified to 81/40.
81% as a decimal is 0.81
8
81 over 200 is the same as 81 divided by 200 (or 81/200), which is 0.405
9^2 is 81 and 3^4 is 81
It is: 85.185% recurring decimals
81 x 355/113 = 254.47 to 2 places of decimals
It is: 72/88 times 100 = 81.'81'% recurring decimals
Two equivalent fractions of 27/81 are: 1/3 and 2/6
81/100 = 162/200 and 243/300
360/810, 3636/8181 are two.
It is: 9*(8+1) = 81
28/54, 42/81