- If one number has a leftmost place that is greater than the leftmost place in another number, the first number is greater than the second number.
Example: 675 is greater than 75 because the first number has a leftmost place of hundreds. 600+70+5
- 75 is less than 675 because the leftmost place is only tens. 70+5
Here is how you write this:
675 > 75 : > = greater than < = less than. You always compare starting with the first number as if reading left to right.
Example: Six hundred seventy five is greater than seventy five, or 675>75.
- To round a number to a given place value, look to the number immediately to the right and round according to these rules.
- If the number is greater than 5, round up. If the number is less than 5, round down.
Example: We want to round 7427 to the nearest tens place (2). So, look at the number immediately to the right (7) and round. The number 7 is greater than 5, so round up (30). The answer is 7430.
Additional Examples: Tens place: 423=420, 25=30. Hundreds place: 565=700, 1270=1000 etc.
- When you write a rounded number, you replace the part not used with zeros.
Examples: Round up 27 to 30. Round down the number 21 to 20.
The sum is the total of two numbers added together.
The numbers that are added together are called addends.
Example: The sum of 5 + 3 is 8
5 and 3 are the addends and they equal 8 when added together.
- The order of the addends does not affect the answer as 5 + 3 is the same as 3 + 5. They both equal 8.
- In subtraction, you subtract the smaller number from the bigger one.
Example: 12 - 4 = 8 This is correct. It is incorrect to try and subtract the bigger number from the smaller one in basic math. For example, the equation 4 -12 could not be performed in basic math because 4 is not big enough to have 12 taken away from it.
Remember: Always place the larger number first.
Remember: You cannot change the order of the equation when doing basic subtraction. The answer will be affected even if you come up with one.
There are two basic types of subtraction.
1. If you have two shoes and subtract or "take-away" one, you are left with the difference, one shoe.
Example: 2 - 1 = 1
2. The second type of subtraction is comparison subtraction.
Example: Mark is 5 feet tall. His sister is 3 feet tall. How much taller is Mark than his sister? The answer would be 2 because 5 - 3 = 2.
- Multiplication is repeated addition.
Example: 2 x 3 = 6 or 2 + 2 + 2 = 6.
The first factor (in a horizontal problem) or the top factor (in a vertical problem) is called the multiplicand.
The other factor is called the multiplier.
x4 Multiplicand 10 x 4 = 40 ten is the multiplier and 4 is the multiplicand
- The idea of multiplication is to simplify adding many numbers. You could do a multiplication problem using addition, but that would take a long time because would you to have to add up many more numbers.
Example: 4 x 3 = 12 whereas in addition, it would look like this... 3 + 3 + 3 + 3 = 12
- Division is often referred to as backwards multiplication. If you take the number 7 and multiply it by 7, the answer is 49. Now you can divide this equation as well.
- Take the number 49 (or the dividend) and divide it by 7(divisor). Your answer will be 7(quotient) or 49 / 7 = 7 (The symbol "/" is the sign for division on the keyboard).
- An easy way to remember your division is to ask yourself this question: 7 will go into 49 how many times? Next, think of a multiple of 7 that is closest to 49 - 7 x 7 = 49, so there is your answer.