I thing you mean 300 and 400,000,001 timesed together (multiplied)
so you could use a calculator
or
400,000,001=400,000,000+1 so
300 times 400,000,001=(300 times 400,000,000) plus (300 times 1)
400,000,000 times 300= (3 times 4=12, count the zeros and add them togethter)=120,000,000,000
300 times 1=300
300+120,000,000,000=120,000,000,300
