@aditi88 said:remainder when 25! is div by 10^7 is?
0?
@aditi88 said:remainder when 25! is div by 10^7 is?
if the answer is 4 * 10^6, than i wud explain.
odrwise it's worthless typing here.
odrwise it's worthless typing here.
@aditi88 said:remainder when 25! is div by 10^7 is?
25! has 6 zeros
so just need to find the last non zero digit of 25! ie 4
but we cancelled 6 zeros in the beginning, hence 25! % 10^7 = 4*10^6
@swapnil4ever2u said:how many 3 digit numbers have their unit digit neither less than the hundred digit nor less than the tens digit ??
when 2 is last digit
1*2
when 3 is last digit
2*3
when 9 is last digit
9*10
so r(r+1) sum from r=1 to 9
285 + 45 = 330
@The_Loser said:77c+47=13d+9after that, how you straight way clicked 971. ?
77c+47=13d+9
77c+38=13d
-c-1 =13d
c has to be 12
@The_Loser said:if the answer is 4 * 10^6, than i wud explain.odrwise it's worthless typing here.
ya crrct plz xplain
@aditi88 said:remainder when 25! is div by 10^7 is?
look 25! is nothing but has last 6 digit as 0s
now cancel these 6 digits with denominator
last nonzero digit of 25! is 4
now as u have cancelled 10^6 multiply it again to arrive at the answer
so 4*10^6
@iLoveTorres said:the "0" you have considered for the mirror effect that will cause confusion will effectively create confusion only if you have considered 01,02,.... to be valid numbers. but according to the question they arent valid so you shouldnt consider "0" for the confusion thing as it wouldnt lead to any confusion. i am not able to put into appropriate words hope this is clear enough
ok.. got it ...
total 81
and ony 10 digits cause the confusion.. 16,18,19,61,68,81,86,89,91,98.
81-10= 71.
@aditi88 said:ya crrct plz xplain
already quite a few explanations out here.
as mentioned 1st do prime factorisation of 25!.
wt you woud get here is 6 zeros.
rest we just have to find the remainder with 10 that is unit digit of remaining number after cancelling 6 zeros.
25! = 2^22 * 3^10 * 5^6 * 7^3 * 11^2 * 13 * 17 * 19 * 23.
cancel 5^6 * 2^6 = 10^6
find unit digit of remaining number.
answer would be 4.
to have the final answer multiply it with 10^6.
final answer - 4 * 10^6
(edited)
as mentioned 1st do prime factorisation of 25!.
wt you woud get here is 6 zeros.
rest we just have to find the remainder with 10 that is unit digit of remaining number after cancelling 6 zeros.
25! = 2^22 * 3^10 * 5^6 * 7^3 * 11^2 * 13 * 17 * 19 * 23.
cancel 5^6 * 2^6 = 10^6
find unit digit of remaining number.
answer would be 4.
to have the final answer multiply it with 10^6.
final answer - 4 * 10^6
(edited)
For how many natural numbers, N the expression N ˛ + N + 1 results in a perfect square?
Question : for how many prime nos. p is p^4+15p^2-1 a prime no.?
P.S. : I do not have the OA...
A cloth merchant says due to slump in the market, he sells the cloth at 5% loss, but he uses a fake metre scale and actually gains 5%. What is the length of the scale?
A- 92.75 cm
B-90.25 cm
C-1900/21
D-90.8
A- 92.75 cm
B-90.25 cm
C-1900/21
D-90.8
@saurav205 said:Question :for how many prime nos. p is p^4+15p^2-1 a prime no.?P.S. : I do not have the OA...
is it 0
@The_Loser said:For how many natural numbers, N the expression N ˛ + N + 1 results in a perfect square?
none??
@saurav205 said:Question :for how many prime nos. p is p^4+15p^2-1 a prime no.?P.S. : I do not have the OA...
p=2 gives 75 (not prime)
odd primes end in either 1,3,7 or 9
1^4 + 15*1^2 - 1 = xx5
3^4 + 15*9 - 1 = xx5
7^4 + 15*9 - 1 = xx5
9^34 + 15*1 - 1 = xx5
since all end in 5, none can be a prime...
@sumit99 said:A cloth merchant says due to slump in the market, he sells the cloth at 5% loss, but he uses a fake metre scale and actually gains 5%. What is the length of the scale?A- 92.75 cmB-90.25 cmC-1900/21D-90.8
95*100/x = 105
x = 1900/21