The question given here has two parts and each part has to be answered separately. In case of both the multiplications, the answer might look to be huge but by applying a simple technique, anybody can do these multiplications without the help of any calculator.
Now let us take the case of first multiplication that is given:
50000 * 700
= 35000000
In this case all the zeroes present has to be written first and then 7 and 5 should be multiplied and put. This will get the answer easily.
Now we take the second multiplication given:
100 * 123478
= 12347800
In this case also the zeroes are simply put on the right side of the number 123478.