81 times 2 cubed is equal to 648.
2/3 x 81 = 54
2 x 40.5 = 81
2
2 27 27 +27 ----- 81
81 ÷ 28 = 2 with remainder 25.
Two goes into eighty-one 40.5 times.
Because 9 times 9 equals 81.
81 x 355/113 = 254.47 to 2 places of decimals
40 with 1 remaining 81 - 1 = 80 = 2 x 40
1 times 81 and 9 times 9 (assuming you meant only whole numbers)
40 with remainder 1.