1660
16.5
6
28
One trick for multiplying by 12 is to multiply the number by 10 and then add two times the number. For example, if you want to multiply 7 by 12, first multiply 7 by 10 to get 70, and then add 7*2=14 to get 84.
80
They are 40 and 40
1680
-1540
1660
16.5
-121
71
1.52
6
1,600 square feet. Multiply the two dimensions - the result is the number of square feet.
Multiply the three-digit number by the one's digit, or last digit, of the two-digit number. That is your first part. Now multiply by the second-to-last digit, or ten's digit, and multiply the result by 10. That is your second part. Add the two parts and that is your answer.
32