How is 7×4 similar to finding 7×2000

You are using 7 in both In the first on you just multiply 7 x 4=28 In the second if you factor out 1000 The problem looks like this 7 x 2 x (1000) 7 x 2 is like the 7 x 4 When you multiply by 10, 100, 1000 etc you just add that many zeroes to the right of the number Here is what it looks like 7 x 2 is 14 then 1000 has 3 0's so add them to 14, 14000

True.  That is why they are the bases.