Twenty one hundreth as a fraction would be 21/100.
Twenty-one hundredths is 0.21
24.01
twenty-three and one hundredth
2101/100
Write it over one hundred. 0.57 = 57/100
One and one hundredth as a decimal is written as 1.01
nothing
21/1000
1 __ 20
1/2 of 1/100 = 1/200
123/100
twenty-one thousand = 21000/1 twenty-one thousandths = 21/1000