What is the product of 4 tens and 2 tens?

40 times 20 equals 800

How did you get the 40? Multiply 4 by ten because it is 4 tens and you get 40. You do the same with 2 tens. Multiply.

40

x20

40 x 0 = 00

then you do put down two zeros. Then you do 40 x 2 and add a 0 to 2 because it is in the place value of tens. So, 40 x 20 = 800. Add 00 and 800 and you get 800. Simple!