Arrange following decimals in descending order:
0.42, 0.27, 0.68, 0.15 
This proceeds in the following steps:
In the given series whole number part of all the decimals are same, so will compare digits at tenths place and arrange them in the descending order in the following steps:
Step 1: We start with comparing the digits at tenths place and decimal with the largest digit at tenths place is to be written at first place in the order, we get:
6 is the largest digit at tenths place of decimal 0.68 from the given series, so it is written in the first place of descending order.
Descending Order Series = 0.68
Step 2: Then we find a decimal whose digit at tenths place is smaller than the digit at tenths place of decimal selected earlier in step 1, but larger than digit at tenths place of remaining decimals and we get:
4 is the digits at tenths place of decimal 0.42
It is smaller than the 6, which is the digit at tenths place of decimal 0.68, but larger than digit at tenths place of remaining decimals
So 0.27 is written next to decimals 0.68 in the descending order and we get series:
Descending Order Series = 0.68, 0.42
Step 3: Then we find a decimal whose digit at tenths place is smaller than the digit at tenths place of decimal selected earlier in step 2, but larger than digit at tenths place of remaining decimals and we get:
2 is the digits at tenths place of decimal 0.27
It is smaller than the 4, which is the digit at tenths place of decimal 0.42, but larger than digits at tenths place of remaining decimals.
So 0.27 is written next to decimals 0.42 in the descending order and we get series:
Descending Order Series = 0.68, 0.42, 0.27
Step 4: Lastly, we are left with only one decimal, whose digit at tenths place is the smallest among digits at tenths place of all the given decimals and it would be written at the last place of the order:
Since, decimal 0.15, whose digit at tenths place is 1 and the smallest among digits at tenths place of all the given decimals, so 0.15 would be written at the last place of the descending order and we get complete series:
Descending Order Series = 0.68, 0.42, 0.27, 0.15

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