Sunday

November 23, 2014

November 23, 2014

Posted by **B.B.** on Tuesday, June 9, 2009 at 7:55pm.

- Math -
**MathMate**, Tuesday, June 9, 2009 at 10:51pmYes, 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

**Answer this Question**

**Related Questions**

Math - I cannot figure this problem out. I have did it several ways and get ...

Math - I need some help. Here is the problem: Give an estimate for the following...

statistics - Give an estimate for each expression in Exercises, Then state ...

Math - Here is the original question: Give an estimate for the following ...

Math - if you use $63.00 divided by 9 to estimate $62.59 divided by 9 $7.00 ...

3rd grade math - i need help!! if the estimate is greater than or equal or 1,500...

math - if you use $63.00 divide by 9 to estimate $62.59, is $7.00 greater than ...

math - If you use $63.00/9 to estimate $62.59/9 is $7.00 greater than or less ...

math - if you use $63.00 divided by 9 to estimate $62.59 divided by 9 is $7.00 ...

Calculus - Oil is leaking out of a ruptured tanker at a rate of r = 19e^(2t) ...