What is the perimeter of a rectangle if the length of the short sides are 5", and the other sides are both y?
2 answers:
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Answer:
a. 1200 f. 900
b. 600 g. 5700
c. 900 h. 4800
d. 300 i. 8300
e. 800 j. 8500
Step-by-step explanation:
First of all, you need to compute the sums. I find a calculator handy for this.
To round to hundreds, you can examine the digit in the next place to the right of the hundreds place. That digit in the tens place needs to be compared to 5. If it is 5 or greater, add 1 to the digit in the hundreds place. After you have done that, set the digits to the right of the hundreds place to zero.
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Alternatively, you can add 1/2 of 100 to the sum, then set the digits to the right of the 100s place to zero. (Adding 50 will only change the 100's place digit if the 10's place digit is 5 or more.) This method doesn't require you do any thinking about the size of the digit; it is purely mechanical.
The sums and their rounded values are ...
a. 1221 ⇒ 1200
b. 568 ⇒ 600
c. 931 ⇒ 900
d. 347 ⇒ 300
e. 798 ⇒ 800
f. 911 ⇒ 900
g. 5681 ⇒ 5700
h. 4766 ⇒ 4800
i. 8328 ⇒ 8300
j. 8507 ⇒ 8500
