Question 1041341: What least number, when divided by 26,36 and 56, leaves the remainders 6,16,36 respectively ?
Answer by Edwin McCravy(20054) (Show Source):
You can put this solution on YOUR website!
n = 26a+6 = 36b+16 = 56c+36
We solve the Diophantine equation
36b+16 = 56c+36
9b+4 = 14c+9
9b = 14c+5
9 is the least integer in that equation
in absolute value, so write all the other
integers in terms of a near multiple
of 9. So we write 14 as 18-4, and 5 is
near 9 so we just leave it as it is.
9b = (18-4)c+5
9b = 18c-4c+5
Divide through by 9
b = 2c-4c/9+5/9
Get the fraction on the left and other terms
on the right:
4c/9-5/9 = 2c-b
The right side is an integer, say P, so
4c/9-5/9 = 2c-b = P
4c/9-5/9 = P
4c-5 = 9P
4 is the least integer in that equation
in absolute value, so write all the other
integers in terms of their nearest multiple
of 4. So we write 5 as 4+1, write 9 as 8+1.
4c-(4+1) = (8+1)P
4c-4-1 = 8P+P
Divide through by 4
c-1-1/4 = 2P+P/4
Get the fraction on the right, other terms
on the left:
c-1-2P = P/4+1/4
The left side is an integer, say Q, so
c+1-2P = P/4+1/4 = Q
P/4+1/4 = Q
P+1 = 4Q
P = 4Q-1
c-1-2P = Q
c-1-2(4Q-1) = Q
c-1-8Q+2 = Q
c+1-8Q = Q
c = 9Q-1
9b = 14c+5
9b = 14c+5
9b = 14(9Q-1)+5
9b = 126Q-14+5
9b = 126Q-9
b = 14Q-1
26a+6 = 36b+16
26a = 36b+10
13a = 18b+5
13a = 18(14Q-1)+5
13a = 252Q-18+5
13a = 252Q-13
13 is the least integer in that equation
in absolute value, so write all the other
integers in terms of their nearest multiple
of 13. So we write 252 as 247+5.
13a = (247+5)Q-13
13a = 247Q+5Q-13
Divide through by 13
a = 19Q+5Q/13-1
Get the fraction on the right and other
terms left:
a+1-19Q = 5Q/13
The left side is an integer, say R, so
a+1-19Q = 5Q/13 = R
5Q/13 = R
5Q = 13R
We could continue as before but this equation is
simpler and we see that the smallest integers Q
and R that solve that are Q=13 and R=5.
So a+1-19Q = R
a+1-19(13) = 5
a+1-247 = 5
a-246 = 5
a = 251
And since n = 26a+6
n = 26(251)+6
n = 6526+6
n = 6532
Checking:
251 181 116
26)6532 36)6532 56)6532
52 36 56
133 293 93
130 288 56
32 52 372
26 36 336
6 16 36 <-remainders check!
Edwin
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