Explanation

We know, the least number of KaTeX parse error: KaTeX doesn't work in quirks mode. digits is KaTeX parse error: KaTeX doesn't work in quirks mode.
If we divide KaTeX parse error: KaTeX doesn't work in quirks mode. by KaTeX parse error: KaTeX doesn't work in quirks mode. we get:
KaTeX parse error: KaTeX doesn't work in quirks mode. as a quotient and KaTeX parse error: KaTeX doesn't work in quirks mode. as a remainder.
Now, if we subtract the remainder KaTeX parse error: KaTeX doesn't work in quirks mode. from the divisor KaTeX parse error: KaTeX doesn't work in quirks mode. then we get:
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode.
Now, if we add KaTeX parse error: KaTeX doesn't work in quirks mode. to the KaTeX parse error: KaTeX doesn't work in quirks mode. digits least number KaTeX parse error: KaTeX doesn't work in quirks mode. then we get:
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode. is the KaTeX parse error: KaTeX doesn't work in quirks mode. digits least number which is exactly divisible by KaTeX parse error: KaTeX doesn't work in quirks mode.
Ans: The 6 digits least number is 100050 which is exactly divisible by 87.

Another way

If we divide KaTeX parse error: KaTeX doesn't work in quirks mode. by KaTeX parse error: KaTeX doesn't work in quirks mode. we get:
KaTeX parse error: KaTeX doesn't work in quirks mode. as a quotient and KaTeX parse error: KaTeX doesn't work in quirks mode. as a remainder.
From this we understand that:
KaTeX parse error: KaTeX doesn't work in quirks mode.
And the number right after that:
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode. is the KaTeX parse error: KaTeX doesn't work in quirks mode. digits least number which is exactly divisible by KaTeX parse error: KaTeX doesn't work in quirks mode.
Ans: The 6 digits least number is 100050 which is exactly divisible by 87.

These precise math questions can also be expressed as:

1. Finding the smallest 6 digit number divisible by 87.
2. What is the smallest 6 digit number that can be divided by 87 without a remainder?
3. How to find the smallest 6 digit number that is a multiple of 87?