For my math warm up questions I did four problems. Each were in a different part of math like divition subtraction multibication and addition. On 28 subtract 7 all you have to know is 8-7 = 1 then add the 2 infront of the one and that gives you your anwer.
Now we’ve got the problem 9×4= 36. All you have to do is 18+18. First do 8+8=16 then do 10+10=20 add them together and you got your anser.
Now 28 divided by 7= 4. All you got to do is count by 7 till you get to 28 and how many 7’s you counted gives you your anwer.
Now 9+4=13. So how I got thought was if your adding with 9’s you take a number from the one your adding to nine and make it a ten then add the rest.