Remark
First of all, you should notice that the number you want must end in 5 to get a remainder of 5. That's because your divisors all end in 0.
Step One
Factor the 3 divisors
40: 2 * 2 * 2 * 5
50: 2 * 5 * 5
60: 2 * 2 * 3 * 5
Step Two
Using these factors, find the LCM
There are 3 twos, 1 Three, and 2 fives.
The LCM is 8*3*25 = 600
Step Three
Find the first number over 1000 that is divisible by 600. That should be 1200 which is 600 * 2
So the answer to your question is 1205
