Mathematics Magazine for Grades 1-12  

4/2004

Whatever is worth doing at all, is worth doing well.
 - Earl of Chesterfield

Grade 6

Theory:

Comparing Decimal Numbers

If there are two decimal numbers we can compare them.  One number is either greater than, less than or equal to the other number.

A decimal number is just a fractional number. Comparing 0.7 and 0.07 is clearer if we compared 7/10 to 7/100. The fraction 7/10 is equivalent to 70/100 which is clearly larger than 7/100.

Therefore, when decimals are compared start with tenths place and then hundredths place, etc. If one decimal has a higher number in the tenths place then it is larger than a decimal with fewer tenths. If the tenths are equal compare the hundredths, then the thousandths etc. until one decimal is larger or there are no more places to compare. If each decimal place value is the same then the decimals are equal.

Solutions from the Previous Issue:

In each of the following proportions solve for the unknown value.

1                  

Solution:

2                                  

Solution:

3                

Solution:

4                

Solution:

Proposed Problems:

1.        Mr. Bloop is rolling small steel disks down a ramp. Each disk is 4 cm in diameter and 5 mm thick. It takes 7 seconds to go down the ramp and the distance traveled from the top to the bottom of the ramp is 119 cm. How many revolutions does a disk make on the way down? Round your answer to the nearest hundredth.

2.        A coil of wire was found lying in the shipyard. Megan wondered if it would be enough to temporarily hold some steel plates in position while they were being welded. The wire was braided steel 1-cm thick. The coil was neatly wound in a single layer around a wooden spool 1.3 meters in diameter. The wire spanned a distance of 56 cm on the spool. She needed 365 meters of wire to do the job. Is the coil of wire long enough for her purposes?

3.        The world's biggest pizza was made in Norwood, South Africa, in 1990. The diameter of the pizza was 37.3 meters. What was the area of the pizza?

Find the circumference of each circle. State your answer in terms of and also round your answer to the nearest tenth.

4.        radius = 12 cm