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How many 4digit numbers (ABCD) can be formed such that A – D = 2? 2
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08 Apr 2016, 02:48
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How many 4digit numbers (ABCD) can be formed such that A – D = 2? A. 2,000 B. 1,900 C. 1,800 D. 1,600 E. 1,500
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Re: How many 4digit numbers (ABCD) can be formed such that A – D = 2? 2
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22 Apr 2016, 02:22
chetan2u wrote: hi, I donot think C should be the answer.. In highlighted portion you have taken following extra ways 1) A=0 and D8 2) A and D as 1 and 9..so 3*100= 300 extra ways ans 1800300 = 1500.
we are looking for AD=2 so any of the two can be bigger.. these two can have values (1,2) ; (2,4) so on till (7,9) so total 7*2 = 15.. another arrangement could be A as 8 and D as 0... D as 8 and A as 0 is not possible as number will become 3 digits.. so the ways A and D can be placed = 14+1=15 ways.. B and C can be placed in 10*10 ways..
Total = 15*10*10=1500
Hi chetan2u, A few observations, highlighted portion might be a typo. It should read: (1, 3) ; (2,4) so on till (7,9) so total 7*2 = 14Also, If A = 8 and D = 0, then AD = 8 and not 2 Here D = 0, not 10



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Re: How many 4digit numbers (ABCD) can be formed such that A – D = 2? 2
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08 Apr 2016, 03:08
Digit A can be filled in 9 ways (excluding 0) Digit B can be filled in 10 ways Digit C can be filled in 10 ways Digit D can be filled in 2 ways (because of modulus AD )
The answer will be 9*10*10*2 = 1800
Ans C



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How many 4digit numbers (ABCD) can be formed such that A – D = 2? 2
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08 Apr 2016, 04:53
raarun wrote: Digit A can be filled in 9 ways (excluding 0) Digit B can be filled in 10 ways Digit C can be filled in 10 ways Digit D can be filled in 2 ways (because of modulus AD )
The answer will be 9*10*10*2 = 1800
Ans C hi, I donot think C should be the answer.. In highlighted portion you have taken following extra ways 1) A=0 and D8 2) A and D as 1 and 9..so 3*100= 300 extra ways ans 1800300 = 1500.we are looking for AD=2 so any of the two can be bigger.. these two can have values (1,3) ; (2,4) so on till (7,9) so total 7*2 = 14.. another arrangement could be A as 2 and D as 0... D as 2 and A as 0 is not possible as number will become 3 digits.. so the ways A and D can be placed = 14+1=15 ways.. B and C can be placed in 10*10 ways..Total = 15*10*10=1500
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Re: How many 4digit numbers (ABCD) can be formed such that A – D = 2? 2
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22 Apr 2016, 00:58
Ans = 1600 (D)
(1,3)(2,4)...(7,9) = 7*2*10*10 = 1400 (2,0), (8,0) = 2*1*10*10 = 200
=> Ans = 1600



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Re: How many 4digit numbers (ABCD) can be formed such that A – D = 2? 2
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23 Apr 2016, 07:50
rathan1488 wrote: Ans = 1600 (D)
(1,3)(2,4)...(7,9) = 7*2*10*10 = 1400 (2,0), (8,0) = 2*1*10*10 = 200
=> Ans = 1600 i think 8 cannot be consider with 0 their mod diff is 8 not 2 hence 1500. Please correct if i calculated anything wrong



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Re: How many 4digit numbers (ABCD) can be formed such that A – D = 2? 2
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23 Apr 2016, 08:38
Bunuel wrote: How many 4digit numbers (ABCD) can be formed such that A – D = 2?
A. 2,000 B. 1,900 C. 1,800 D. 1,600 E. 1,500 Good one... ABCD is a four digit number , so A must be a non zero digit Further A – D = 2 Lets draw a table Attachment:
A  D Table.PNG [ 9.21 KiB  Viewed 2337 times ]
So we have AD 15 possible arrangements Now go for B & C Possible arrangements Attachment:
B  C.PNG [ 1.52 KiB  Viewed 2332 times ]
For B = The digit can be any number from 0  9 ( 10 digits ) For C = The digit can be any number from 0  9 ( 10 digits ) So, The possible arrangements is 15 x 10 x 10 = 1500
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Re: How many 4digit numbers (ABCD) can be formed such that A – D = 2? 2
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23 Apr 2016, 10:53
OptimusPrepJanielle wrote: chetan2u wrote: hi, I donot think C should be the answer.. In highlighted portion you have taken following extra ways 1) A=0 and D8 2) A and D as 1 and 9..so 3*100= 300 extra ways ans 1800300 = 1500.
we are looking for AD=2 so any of the two can be bigger.. these two can have values (1,2) ; (2,4) so on till (7,9) so total 7*2 = 15.. another arrangement could be A as 8 and D as 0... D as 8 and A as 0 is not possible as number will become 3 digits.. so the ways A and D can be placed = 14+1=15 ways.. B and C can be placed in 10*10 ways..
Total = 15*10*10=1500
Hi chetan2u, A few observations, highlighted portion might be a typo. It should read: (1, 3) ; (2,4) so on till (7,9) so total 7*2 = 14Also, If A = 8 and D = 0, then AD = 8 and not 2 Here D = 0, not 10 Hi there were typos corrected.. Thank you
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Re: How many 4digit numbers (ABCD) can be formed such that A – D = 2? 2
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29 Nov 2019, 09:28
Bunuel wrote: How many 4digit numbers (ABCD) can be formed such that A – D = 2?
A. 2,000 B. 1,900 C. 1,800 D. 1,600 E. 1,500 Let's make the difference between A and D as 2. First lets consider evens: 2 0 0 2 2 4 4 2 6 4 4 6 8 6 6 8 Odds: 1 3 3 1 3 5 5 3 7 5 5 7 9 7 7 9 All Except 0 2 don't work because that won't give us a 4 digit number. Leaving 0,2 we have 15 choice. That's a straight E. But to actually calculate, A and D at extremes can take 15 values, The middle two digits can take all 10 digits possible So we have 15*10*10 1500 Answer E
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Re: How many 4digit numbers (ABCD) can be formed such that A – D = 2? 2
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