1 2 3 4 () 6 7 8 9 what to fill in and why In fact, to be good at observation, we should fill in a sign that is.. 1234 <6789

1 2 3 4 () 6 7 8 9 what to fill in and why In fact, to be good at observation, we should fill in a sign that is.. 1234 <6789


= =
Just fill in your reward
In the order of integers



1 2 3 4 () 6 7 8 9 what to fill in the middle?





1 2 3 4 5 6 7 8 9 = 1 can only be added or subtracted


1+2+3+4+5-6-7+8-9=1