Describe two different ways that you could find the product 8 x 997 using mental math. find the product and explain why your methods work.

One method is to round 997 up to 1000, multiply by 8, and then subtract 8 times 3. This would give you the solution of 7976.

Another method (Which I personally wouldn't use) is to recursively double 997. This is more difficult, although effective. After you double 997, double the resulting number, and then double the resulting number from that, you have the solution. This is because 2^3 is 8. 

38+105= 143, 39+104=143, and you will find then adding the numbers on opposite sides, moving inwards yields the answer 138 every time. because of this, you’re going to multiply 138 times the number of pairs, which is 34. therefore, 34*138= 4692(i’m sorry if it’s the wrong numbers, but it’s the right concept)