divisiblity

how to check if 144255 + 192255 is divisible by 49 or not

25 Answers

1
Akand ·

chem sumwher a multiple will cum which is also a multiple of 49...........
thts y check for 7 first.......if no,forget it...........if yes,then do for 49 at tht time

24
eureka123 ·

ok.................[1]

62
Lokesh Verma ·

@eureka..

skip this for jee

come back after that :)

this is olympiad stuff

24
eureka123 ·

@ rajat..........can u explain what u wrote...........i cant understand...[2][2]

1
rajat sen ·

1
chemistry organic ·

dog/s tail.......

49,,,........9.....8......7.......6......not 9.....1......9......1

1
Akand ·

sorry mistake......
for 49..........it shud be divisble by 7 also.................
ok 1st case
144255...........4 6 4 ..repeats every 2 times....so units digit is 4...
192255........2 4 8 6 2 every 4 times........so last digit is 8....
when u add.........last digit of sum is 12....

for 7.......7 4 1 8 5 2 9 6 blah blah...
for 49...9 8 7 6 ........but no 2.......
so not divisible

1
Akand ·

sorryyyyyyyyyyyyyyyyyyyyyyyyyyy.............
im mad today...............

1
chemistry organic ·

u have wrote 7,9,3,1,...can u tell me wat r they????????????

units place of wat????????????

1
chemistry organic ·

omg!

they r units plce of powes not multiples....forgive me!i m done!

why r u confusing between powers and mutiples...its not that difficult

1
Akand ·

dude.........they are not powers...........they are units place of d multiples

1
chemistry organic ·

if 2 doesnt in powers doesnt signify its not divisible.....

1
chemistry organic ·

mutiples dude not powers dude....

1
Akand ·

for 49..........it shud be divisble by 7 also.................
ok 1st case
144255...........4 6 4 ..repeats every 2 times....so units digit is 4...
192255........2 4 8 6 2 every 5 times........so last digit is 2....
when u add.........last digit of sum is 6....

for 7.......7 9 3 1 7...
6 doesnt cum so it is not divisble................

1
chemistry organic ·

multiples of 7 are 7,14,21,28,......
not 7,49,243,......

1
Akand ·

dude chem............for 49........last digits are not enuf.......u need more........thts y i have taken for 7

1
chemistry organic ·

so last digits 9 , 8 , 7 ,6 ,5 ,4 , .....so it could be divisible...just need to check how to prove....

1
Akand ·

chem..........i was seeing for d last digits of multiples of 7...........not 49.............

39
Dr.House ·

sry akand

1
chemistry organic ·

for 7.......7 9 3 1 7...

why r u going multiplying with 7......u just need to do this....
49*1
49*2
49*3
.....and so on

1
Akand ·

dude mathi.............if it is divisible by 49 then it surely means it is divisible by 7.........I meant tht

39
Dr.House ·

2vicky: use congruencies

1
chemistry organic ·

@AKAND I FOUND A MISTAKE IN YOUR LAST STEP.......

1
Akand ·

sorry mistake......
for 49..........it shud be divisble by 7 also.................
ok 1st case
144255...........4 6 4 ..repeats every 2 times....so units digit is 4...
192255........2 4 8 6 2 every 4 times........so last digit is 8....
when u add.........last digit of sum is 12....

for 7.......7 9 3 1 7...
2 doesnt cum so it is not divisble................

1
Vivek ·

but acc to the ans it is divisible

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