Crack the code

Can you crack this code? For Math's we had to figure out a code on a you tube video. we got a number of combinations that it could be. but the thing is it isn't just the combination its in other ones. it was a three digit code. and the combinations we got were 682, 645, 206, 738, 780. for the 738 none of the numbers were right so we remove all the 7's, 3's and 8's. now our only numbers are 0 2 6 and 4 5. the 6 can't be in it. so we don't add it. a five wont be in it so take that away. now our numbers are 402. now It can go in any order 402 or 042. i'm going with 402. what do you think it is? And I guess the learning behind this was trial and error also paying attention. I found it hard to jigure it out the first time and easy to do it the second heres a picture and video!