How do you know that 361 + 283 is greater than 500 without finding

the sum?

Because you already see that the 3 plus 2 is 5 plus some numbers

You would estimate first look at the 100's place 3+2=5 so we already have 500 so we know that the sumis greater than 500 because is you at 61+83 with 500 its a larger number than just 500