First, to solve this, you should understand a bit of algebra, otherwise, it'll be a bit harder to solve the problem. Here's your quick introduction to it:
Algebra is a part of math where you use variables instead of numbers.
For example:
11111
+23456
_____
turns into
AAAAA
+BCDEF
_____
if:
A=1
B=2
[3 lines ommited]
F=6
The question does this but turns it into symbols.
How to solve it?
Step 1. There is only 1 3-digit number: 100
You now have the symbols for 1 and 0.
Step 2. Find 11 and Put the correct puzzle piece in the right spot according to where 11 (as 2 symbols) and the piece with 11 in.
Step 3. Do Step 2 but with 10 instead. To the left is the symbol for 9.
Step 4. 98 is 2 to the left, above it is 88. You've found 8!
Step 5. Repeat Step 2 but with 8.
Step 6. To the left to 8 is 7, so repeat step 2 but with 77.
Step 7. Find a new symbol (or 2) in the 77 block (i.e. 66), and keep all this repeating up.
In this way, you are guaranteed to find the answer if you do it correctly.
If you didn't get my quick algebra course earlier in the description, visit https://education.nsw.gov.au/teaching-and-learning/student-assessment/s… for more.