Find the least 4-digit number which is exactly divisible by 8, 10, and 12.

The smallest 4-digit number is 1000.

The least number which is exactly divisible by 8, 10, and 12 will be their L.C.M.

L.C.M. of 8, 10, and 12:

L.C.M. of 8, 10, 12 = 2 × 2 × 2 × 5 × 3 = 120.

By dividing smallest 4-digit number 1000 by 120,

We find that 1000 is not exactly divisible by 120.

If we subtract 40 from 1000, we get 1000 - 40 = 960, which will be divisible by 120. But 960 is a 3-digit number. The next number to 960 which is divisible by 120 is 960 + 120 = 1080.

Therefore, the required 4-digit number divisible by 8, 10, and 12 is 1080.