N is multiplied by 54. The last two digits of this product are 68. When N is multiplied with 46, find the last two digits.
A 2009 digit numberNote- This question is taken from a class 5 Math talent exam paper, thus the title.
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how can a 5 grader solve like this
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Bcoz it is simple multiplication thatz applied.Though it is a far cry its not out of syllabus
Elegant! Dayum! XD
how did yo got 42 and 92
We are told there is just one solution, so we needn't worry about multiple options.
Some number times 54 is 68. The last digit may be 2 (2 4=8) and since there is nothing to be carried and 54 2=208 which has no tens digit, the second to last digit may be 4 (4 4=16). 42 54=2268.
42*46=92+1840=1932. The answer is 32.
Let's call that number: a.
We have:
5
4
a
≡
6
8
[
1
0
0
]
which means
−
4
6
a
≡
6
8
[
1
0
0
]
hence
4
6
a
≡
−
6
8
≡
3
2
[
1
0
0
]
Cool!!!!!!!!!!!!!!!!!
Yep, but not sure how to proceed as a fifth grader.
It can be done very quickly this way
Given that n × 5 4 when divided by 100 leaves a remainder 68
⇒ n × − 4 6 leaves a remainder 68
⇒ n × 4 6 leaves a remainder - 68 i.e -68+100 = 32
I think this problem can be solved without any knowledge on number theory......how?????lets see!!!!!!!First........the last no of the given product is 8...4 can form this no. only after multiplication with a number ending with 2 or 7.......here lies the sums beauty!!!!!! '6'of the no 46 when multiplied with any of 2 or 7 yields the last number as 2....!!!!!!So we are confirmed that the last no. of the required product is 2............!!! now the second-last number of the given product is 6.........now let the second last no.of the given number be "x".....so 2 eqations may be formed
4x+(5.2)=(something)6 or
4x+(5.7)=(something)6
but second equation is not possibe as sum of a even and odd no.always yields an even no.
so for first eqation the soln of "x"are 4 or 9 as the last digit of
(5.2) is 0 so when multiplied by 46 yields the no.as 3........thats it!!!!!!!!!!!!!!!!!!!!!!
That's how I did it..
i think there is a mistake. in your eqn 4x+5.7 . if your last digit happens to 7. then there will be a carry over of 2. which in turn obeys your condition of odd+even+even will not end in even . but that part is important i guess. so, which concludes the last term is going to be 2.
Yeah i did the sm way... It is more easier!!
yey i did it...but i think that the last two digits could also have been 9 and 2.it would yield the same result that is last 2 digits after multiplying coul have been 52 as well
what do you want say . plz be clear in your words
Cooool Que bro...... @Krishna Ar it was very easy The product of last two digits with two digits doesnt matters how many digits it is... It is clear that last digit of the no. Is 2 and then after let the second last digit be p P 2 ×54 =4P+10 now as second last digit of product is 6 and greatest posiibility of coming 6 is 26 by regarding conditions thus 4P+10=26 thus P=4 There fore last two digit of 2009 digit number is 2 and 4 By order Now multiplying it By 46 We get the desired digits as 2 and 3 by order Thats it.....
COOL problem bro
Will you please delete the question "Are you smarter than a 5th grader- Part 6· Level 4 (110 points) " from your set since I have completed all the other questions from your set but still haven't been able to make it to the leaderboard .
Thanks for the same .
Yeah, I 'll do it. But please don't post this as a solution. It is not really good to clog the discussion of this problem. Reply to me , so that I can delete your solution.
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We have a number a 1 a 2 a 3 . . . . a 2 0 0 8 a 2 0 0 9 .
So, if we multiply a 2 0 0 8 a 2 0 0 9 x 5 4 = ( 1 0 a 2 0 0 8 + a 2 0 0 9 ) x 5 4 = . . 6 8 , we obtain that the solution are ( a 2 0 0 8 , a 2 0 0 9 ) = { ( 4 , 2 ) , ( 9 , 2 ) } . So thats mean that: 4 2 X 4 6 = . . 3 2 9 2 X 4 6 = . . 3 2