Question

Find the least number that when devided by 16,18 and 20 leaves a remainder 4 in each case but is completlely divisible by 7

Answer 1

Heya user,

The no. is of the form --> [ multiple of LCM of (16,18,20) ] + 4
Now,

LCM [ 16,18,20 ] = 720;

Hence, our no. is of the form 720x + 4;

Now, 7 | 720x + 4 => 7 | 7(102x) + 6x + 4 => 7 | 6x + 4;

Therefore, least value of x for which 7 | 6x + 4 ----> is 'x' = 4
Thus, the req.d no. is 720(4) + 4 = 2884..... ☺

Answer 2

the number is 2884....