A review of Decimals

Hi my dear students,

this unit is called Decimal Numbers, those who have a decimal point.The decimal point is the most important part of a Decimal Number. It is exactly to the right of the Units position. Without it, we would be lost ... and not know what each position meant.

PLACE VALUES
Each place in a number has a different place value. Below is a chart that shows the different place values in a number. As we look at this diagram, notice the spelling changes from the places to the left of the decimal point (which represent places for whole numbers) and the decimal places to the right of the decimal point.


Practice 1 and Practice 2. Game

ORDERING DECIMALS

Ordering decimals can be tricky. Because often we look at 0.42 and 0.402 and say that 0.402 must be bigger because there are more digits. But no!

If you follow the following method you will see which decimals are bigger. 

• Set up a table with the decimal point in the same place for each number.
• Put in each number.
• Fill in the empty squares with zeros.
• Compare using the first column on the left, and pick out the highest in order.
• If the digits are equal move to the next column to the right until one number wins.

 Practice on this links: Comparing decimals and Ordering decimals.


ROUNDING DECIMALS
Rounding off a decimal is a technique used to estimate or approximate values. Rounding is most commonly used to limit the amount of decimal places. Instead of having a long string of decimals places, or even one that goes on forever, we can approximate the value of the decimal to a specified decimal place.

When to Round Up

Rounding up means that we increase the terminating digit by a value of 1 and drop off the digits to the right. If the next place beyond where we are terminating the decimal is greater than or equal to five, we round up.

When to Round Down

If the number to the right of our terminating decimal place is four or less (4, 3, 2, 1, 0), we round down. This is done by leaving our last decimal place as it is given and discarding all digits to its right. 

Practice on this link.Play a game.


OPERATIONS WITH DECIMALS

In this post we will give a review of some basic operations with decimals. Performing these operations with decimals is like doing them with whole numbers. The difference is the way that you need to keep track of the decimal point.


ADD
Practice 1, Practice 2, Practice 3, Practice 4

SUBTRACT
Practice 5, Practice 6, Practice 7

MULTIPLY
Practice 8, Practice 9, Practice 10

DIVIDE
Practice 11, Practice 12, Practice 13, Practice 14

Play a game

Take care!

ALICIA