How To Estimate Product by rounding to single...?

Question

Estimate each product by rounding to a single nonzero digit, then find the actual product.

24 X 18

If You Multiply it you get 432
then if you round it you get 400?
so are those my two answers? or is there more to this?
and how do i know what to round it to.
and what does nonzero digit mean no zeros? or zeros?

You're Right!
If You Round 24 to 20 and 18 to 20 you get 400.

I multiplied 24x18 and got 432 and then rounded 432 to 400.

Answer 1

I think you might have this a little wrong because the way I was taught, you would round 24 to 20 and 18 to 20 which turns this problem into 20*20=400.