math

Quote:

A4273B is 6 digit no. in which A and B are digits and the no. is divisible by 72. Find A and B

this number is

N = 100000A + B + 42730 and

N mod 72 = 0

42730 mod 72 = 34

100000 mod 72 = 64 so

N = 64A + B + 34 = 0 (mod 72)

(64A+34) mod 72 = 72 - B

at this point I don't know anything more clever than making a small table and looking for A such that

(64A+34) mod 72 is within 9 of 72

doing this you find A=5 and B=6

542736 / 72 = 7538

lol:

A4273B is 6 digit no. in which A and B are digits and the no. is divisible by 72. Find A and B

If the number is advisable by 72, it must be dividable by all the factors of 72
So it will be divisable by 2,3,4,6,8,9,12,18,24, and 36

If you don't know how to check for these you could look here. We did this at length recently.

http://web2.0calc.com/questions/viewtopic.php?f=2&t=7778&hilit=divisibility

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