Each equation is just multiplying 7 and 2.
The zeros are added at the end depending on the number of zeros being multiplied.
7×2=14
Now if we do 7×20=140
One zero is added at the end because there is only one zero being multiplied which is the 0 in the ones place for 20.
7×2,000=14,000
Three zeros are added because again there is three zeros being multiplied.
If the equation was 70×20=1400
Two zeros are added because there are two zeros being multiplied in the ones place, and so on.