Answer: Hi! the notation 7×10^3 means 7*10*10*10, where 3 is the exponent.
You can think this notation as how many zeros you can add to the left (or right if the exponent is negative) of a number.
so 7×10^3 has an exponent equal to 3, so you add 3 zeros and get : 7000.
if we do the multiplication, 7*10*10*10 = (7*10)*10*10 = 70*10*10 = (70*10)*10 = 700*10 = 7000.