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Clocks and Calendars
How many palindromes in a clock from noon to midnight ? Example 05.45 is a palindrome
Read Solution (Total 4)
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- At 12 o' clock, there is only one way to get a palindrome and it's at 12:21
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At 1 o' clock, there are 6 ways to have a palindrome and they are
1:01, 1:11, 1:21, 1:31, 1:41, 1:51
At 2 o' clock, there are 6 ways to have a palindrome and they are
2:01, 2:11, 2:21, 2:31, 2:41, 2:51
etc... all the way up to 10 o' clock (but not including 10 o' clock)
There are 6 palindromes for each hour in the list above and there are 9 hours from 1 o clock to 9 o clock. So there are 6*9 = 54 palindromes from 1 to 9 o clock
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From 10 o' clock on to midnight, there are only 2 ways to get a palindrome and they are:
10:01, 11:11
So there are 1+54+2 = 57 palindromes total - 10 years agoHelpfull: Yes(10) No(4)
- here ans is 57.
given 5.45 is a palindrome.starting number is 5 ending number is also 5.so from 1-2 O'clock=1.01,1.11,1.21,......1.51 (after 1.51 it is 2.00 pm starts).
2-3 O'clock=2.02,2.12......2.52 like wise 1-9 has (9*6)=54
but between 10-11(one palindrome that is 10:01,and 11-12=11.11(1 palindrome)).
so 54+2=56 and 12-1 has 1 palindrome that is 12.21
so 56+1=57
- 10 years agoHelpfull: Yes(2) No(0)
- 57 palindromes
- 10 years agoHelpfull: Yes(1) No(1)
- ok fine 57 will be the one
- 10 years agoHelpfull: Yes(1) No(0)
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