Respuesta :

so if you have 9 cats and they each have 9 kittens, then a reasonaable estimate is 10 times 9 since 10 is close to 9 so that is 90 and the answer is 81
you would knwo if you got 988387479 kittens if you got a problem because that is nowhere close to 90

and who do you call? ghostbusters!
Estimating helps you check your reasonableness by getting close to the actual answer you will get.