Math problem! need help i suck in math its pretty simple. i just need someone to explain to me how you check?

Question

check by estimation.

ok, ill give a very simple problem

6,350 x 2

how would i multiply and check that by estimation.

please explain to me how you check by estimation. i know the answer i just need to learn how to check by estimation. thanks.

btw - this is not homework. im just trying to study.

thank you.

Answer 1

6, 350 x 2 = 12, 700

if you estimate it it'll be 10, 000

cuz the number after one is under 5 so u wont add 1

just like rounding

Answer 2

yes, the general rule of 'estimation' is to use simpler values.  so multiplying

27 * 98

is.. well, real arithmetic

but you can estimate by multiplying

30 * 100 = 3000

which is easy.  The goal is to pick values which are easy to work with, and still close to the original values.  And in this case, since our estimating values are both higher than the real values, we know that the real answer is 'close to but LESS than' 3000