Ok so first you set the equation up.... then you know that 13 can’t go into 4 so u put 0 above 4... then you have to see how many times can’t 13 go into 40 which is 3 times because it will equal 39... so 40-39=1.... so then you bring your 3 down so your number should now be 13 and 13 can go into 13 one time because it is 13.... so that’s how the answer is 31 :)