You can count by fives by adding five to the previous count.
If you start with a zero then each number will end in either 5 or 0.
The numbers that you would count if you started with 0 and counted by fives would be:
0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100.
If you start the count with another number, then just add five to the last count. For example:
1, 6, 11, 16, 21, 26, 31, 36, 41, 46, 51, 56 and so on.
Notice that there is a regular pattern in these counts. Every other number ends with the same digit.
Wednesday, 30 November 2011
Counting by Fives
Counting by Threes
You can count by three's by adding three to the previous number.
The numbers that you would count if you started with 0 and counted by threes would be:
0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33 and so on.
The numbers that you would count if you started with 1 and counted by threes would be:
1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31, 34 and so on.
Counting by Twos
Counting by twos is sometimes called "skip counting" because every other number or count is skipped. Each count is two more than the previous count.
If you counted by twos and started with 1 then the blue boxes would have the counts (1, 3, 5, 7, 9, 11)
If you counted by two's and started with two then the white boxes would have the counts (2, 4, 6, 8, 10, 12).
Ascending & Descending
Ordering Ascending Numbers
Numbers have an order or arrangement. The number two is between one and three. Three or more numbers can be placed in order. A number may come before the other numbers or it may come between them or after them.
Example: If we start with the numbers 4 and 8, the number 5 would come between them, the number 9 would come after them and the number 2 would come before both of them.
The order may be ascending (getting larger in value) or descending (becoming smaller in value).
Ordering Descending Numbers
Numbers have an order or arrangement. The number two is between one and three. Three or more numbers can be placed in order. A number may come before the other numbers or it may come between them or after them.
Example: If we start with the numbers 4 and 8, the number 5 would come between them, the number 9 would come after them and the number 2 would come before both of them.
The order may be ascending (getting larger in value) or descending (becoming smaller in value).
Comparing Numbers - Numerals to 20
| Symbol | Meaning | Example in Symbols | Example in Words |
| > | Greater than More than Bigger than Larger than | 7 > 4 | 7 is greater than 4 7 is more than 4 7 is bigger than 4 7 is larger than 4 |
| < | Less than Fewer than Smaller than | 4 < 7 | 4 is less than 7 4 has fewer than 7 4 is smaller than 7 |
| = | Equal to Same as | 7 = 7 | 7 is equal to 7 7 is the same as 7 |
comparing
| Less | $ | ||
| More | $$$$$ | ||
| Same | ****** | ||
| Same | ****** | ||
| More | (((((((((( | ||
| Less | (((((( |
Subtracting Three Digit Numbers
Subtracting Three Digit Numbers
How to subtract three digit numbers (for example 658 - 472).
- Place one number above the other so that the hundreds', tens' and ones' places are lined up. Draw a line under the bottom number.
658 472- Subtract the digits in the ones' place column (8 - 2 = 6) and place the answer below the line in the ones' place column.
658 472 6- Subtract the numbers in the tens' place column (5 - 7 = ?). Borrow one from the hundreds' place to make the top value larger than the bottom value. After this is done, subtract (15 - 7 = 8) and place the 8 below the line in the tens' place column.
5658 472 86- Subtract the digits in the hundreds' place column (5 - 4 = 1) and place the answer below the line in the hundreds' place column
5658 472 186
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