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(#M40002610) TCS Numerical Ability question Keep an EYE

How many 2s are between 1 and 1000?

Asked In TCS Debabrata Bej (13 years ago)

Unsolved Read Solution (18)

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@SI-IW@NI 12U13EY  (13 years ago)

no. of 2's from 1 to 10=1
but additional case arouses for tens n hundred places,i.e.,for no. b/w 21to30n200to300--
for 21to30=10 additional twos in every hundred count
for 200to 300=100 additional twos to both of the above cases
so toal no. of 2's would b=1*(1000/10)+10*(1000/100)+100*(1000/1000)
=100+100+100
=300
so, 300 would be correct n i apolozise for my just previous solution

Is this solution Helpfull? Yes (18) | No (3)  

astha   (13 years ago)

no. of 2's bet 1 to 100 = 20
101-200 = 21
201-300 = 120
301- 400= 20
401-500, 501-600, 601-700, 701-800, 801-900, 901-1000=20
adding 20*8+21+120= 301

Is this solution Helpfull? Yes (5) | No (4)  

pavankumargvs  (13 years ago)

@harish.............. u forgot to take 20........... while coming to answers
consider only 2's in ones place (for clear cut explanation)
- 2,12,32.....92.............with in hundred(10)
102,112,122,132,142........with in two-hundred(10)like wise upto thousand we will gt 10*10=100..... similarly check for tens and hundredth place total is 100+100+100=300..............

Is this solution Helpfull? Yes (4) | No   

Shubham  (13 years ago)

300
the no of 2's between 1 and 100 is 20, and same is for between 301 and 400, 401 and 500, and so on . but in case of the range 201 to 300, 100 additional 2's will be there. so the total no of 2's between 1 and 1000 will be 20*10+100=300

Is this solution Helpfull? Yes (4) | No   

tushar  (13 years ago)

200
any no from 1 to 9 appears 2o time from 1-100
therefore from 1-1000 it will be 20*10=200

Is this solution Helpfull? Yes (3) | No (3)  

harikrishnan  (13 years ago)

300 2's are there.... for 0-9 single digit 1*10pow(1-1)=2
for 00-99 2digit 2*10pow(2-1)=20
for 3digit 000-999= 3*10pow(3-1)= 300

Is this solution Helpfull? Yes (3) | No   

Pratyush Rai  (13 years ago)

ok...sorry with the solution I gave..(Common man's common thinking caught a common mistake)
I missed a 2 in every series 0f 100, so total no of 2's=290+10=300 !!

Is this solution Helpfull? Yes (2) | No (1)  

Pratyush Rai  (13 years ago)

for every series of 100 except that from 200-300 number of 2's=
=(2 @ ten's place+ 2@ unit's place in a series)*9
=(10+9)*9=171
and that for the 200-300= (2-at 100's place)+(2 @ ten's place)+(2 @unit's place)
=100+10+9=119
hence the answer is =171+119=290
//here's a common man's logic...I don't know how every one ended up with 300!!

Is this solution Helpfull? Yes (1) | No (4)  

raman  (13 years ago)

we use the formula 3b^2.ans is 300.if b is base 10.if we want 1 to 100 to find 2 we use 2b.

Is this solution Helpfull? Yes (1) | No   

ssour  (13 years ago)

300 is seem the answer.........

Is this solution Helpfull? Yes | No (1)  

Harsh Gupta  (13 years ago)

between 1 to 100 2 12 21 22 23 24 25 26 27 28 29 32 42 52 62 72 82 92
total no == 18
so between 1 to 1000 == 18 * 10 == 180

Is this solution Helpfull? Yes | No (14)  

@SI-IW@NI 12U13EY  (13 years ago)

since in 1 to 10 there could be only a single 2
from 11 to 20 there could be there could b 2 2's
from 21 t0 30 there could be(1(only one could occur at ones place)+9(since there exists one 2 at every tens place from 21 to 29))
from 31 to 40 only single 2
similarly from 41 to 50,51to60,61to70,71to80,81to90,91to100 there are total 6*1=6 2's
so total 2.s from 1 to 100=1+2+10+2+6
=19
similarly from 100 to 200=19+1(additional for hundreds place)
=20
from 201 to 300=19 + 99(for hundreds place)=118
while 301to400,501to600,601to700,701to800,801t0900,901to10000 r similar to 1to101 so total from 301to1000=6*(no. of twos from 1to101)
=6*19
=96
hence total 2's from 1 to 1000=19+20+118+96
=233

Is this solution Helpfull? Yes | No (12)  

ROHAN SURVE  (13 years ago)

516
as 0-9 except 2 r 9 nos.
for no 1000- 0
so consider 3digit nos
3 possibilities- 1 '2' or 2 '2's or 3 '2's
for 3digit no with only one 2, no of 2=3*(9c1)
with two 2's, no.=3*2*{(9c1)(9c1)}
so total=516=27+486+3

Is this solution Helpfull? Yes | No (4)  

Shailendra  (13 years ago)

20 is the ans...

Is this solution Helpfull? Yes | No (3)  

Saurabh Singh Chauhan  (8 years ago)

300 is right one

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yamini  (6 years ago)

200
In every 100 there must be 20 2's will come so from 1 to 1000 it will be
20 *10=200

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sandeep  (6 years ago)

20
in uint digit between 1 to 100 we get "10" 2 s numbers
similarly ten digit between 1 to 100 we get "10" 2s numbers
add 10+10=20

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rajashree  (6 years ago)

from 1 to 100 there are 19
so 1 to 1000 there are --190 2's

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