Brenda says a good estimate for 50 * 31 3/4 is 800. is this correct? Explain.

No, it would not be a good estimate. If you make 31 3/4 into 32 then multiply 50x32 you get 1,600

At first glance, it seems like a good estimate; big numbers make bigger number.

But, this is multiplication, which means big numbers will make an extraordinarily big number, in proportion to the numbers themselves.

If you round 31 3/4 up to 32, you can multiply that by 50. To make the estimate easier, multiply 50 by 2,

50 x 2 = 100

Take the zeros off 50 and 30 to make this a bit simpler, and multiply 5 by 3,

5 x 3 = 15

Add each of the zeros you took off to the 15 to make 1500 (1 zero was taken off 50, and 1 off of 30),

And then add 1500 to that other 100

1500 + 100 = 1600

A good estimate for 50 x 31 3/4 would be 1600, not 800.

Therefore,

No. Brenda's estimate of 800 is NOT a good estimate.