# Math

posted by .

Here is the question: Give an estimate for the following expression. Then state whether you believe that the exact answer is greater than or less than the estimate. Explain how you decided, The original question is this 54*23. Here is what I've answered: 50*20. I rounded down. 54 went to 50 and 23 to 20. 54*23=1242 50*20=1000. The exact answer is greater than the estimate. I rounded 12 to 10 and 26 to 30.

• Math -

Yes, your method satisfies what the teacher needs, namely give an estimate of the value, and be able to state whether the exact answer is higher or lower than your estimate.

If you want to have a closer estimate (or even the exact answer), here's what I would do, knowing that you already know how to multiply a number by 11 mentally.

54*23
=55*23 - 1*23
=11*(23*5) - 23
=11*115 - 23
=1265 -23

1265 is the estimate, it is an over estimate.
The exact answer can also be calculated mentally as 1265-23=1242

Note: To multiply a number by 5, add a zero and divide by 2.
23*5 = 230/2 =115

## Similar Questions

1. ### Math

I need some help. Here is the problem: Give an estimate for the following expression. Then state whether you believe that the exact answer is greater than or less than the estimate. Explain how you decided. Here is what I have for …
2. ### Math

I cannot figure this problem out. I have did it several ways and get conflicting answers. Give an estimate for the following expression: 12*26. Then state whether you believe that the exact answer is greater than or less than the estimate. …
3. ### Math

Here is the original question: Give an estimate for the following expression: 978*66. Is the exact answer going to be greater than or less than the estimate?
4. ### Math

Here is the question: Find the exact value of the following expression: 6*22*5. Use any mental calculation technique you choose. Name the technique. Here is what my answer looks like: 6*22*5 (6*5)*2*11 (30*2)*11 60*11=660 I multiplied …
5. ### statistics

Give an estimate for each expression in Exercises, Then state whether you believe that the exact answer is greater than or less than the estimate. Explain how you decided. Use a calculator to check the accuracy of your estimate. 978 …
6. ### calculus

consider the initial value problem dy/dx=y^2+1, y(0)=0. estimate y(2) 1) use h=1 to compute your estimate I got x1=1 x2=2 y=1=1 y2=3 2)use h=1/2 to compute your estimate I got x1=1/2 x2=1 x3=1.5 x4=2 y1=1/2 y2=9/8 y3=289/128 y4=5.306671143 …
7. ### Calculus

Can someone explain this question to me? What intervals should I use to test whether or not the graph is concave up or down. I know that no points or equations are given so we have to estimate. Here is the URL for the graph. imgur
8. ### Math

if you use \$63.00 divided by 9 to estimate \$62.59 divided by 9 \$7.00 greater than or less than the exact answer?
9. ### math

how do you estimate fractions? I know how to estimate numbers and decimals but the questions wants us to estimate fraction sand have the answer in fraction form. the question is : 2 1/10 divided by 1 1/5= how would these be estimated?
10. ### Math

Explain how you can tell if your estimate answer is greater or less than exact answer to a multiplication problem

More Similar Questions