Math Lessons

SINUS

admin — Mon, 20 Sep 2010 12:39:01 +0000

Trigonometry Intro

admin — Fri, 10 Sep 2010 13:36:33 +0000

Decimal Multiplication

admin — Thu, 15 Apr 2010 14:45:43 +0000

Suppose you want to multiply 25.3 by 0.46.
Pretend that you’re multiplying numbers without decimal points:
Now you need to find out where the decimal point goes.
To do this, notice that 25.3 has one digit after the decimal point, and that 0.46 has two digits after the decimal point.
Place the decimal point in the answer so that it has three digits after the decimal point.

Adding fractions with unlike denominators

admin — Mon, 12 Apr 2010 17:45:48 +0000

Suppose you want to add the fractions 3⁄7 and 4⁄5.
To get the numerator of the answer, cross-multiply. In other words, multiply the numerator of each fraction by the denominator of the other.
Add the results to get the numerator of the answer.
To get the denominator, just multiply the denominators of the two fractions.

Adding Decimals

admin — Fri, 02 Apr 2010 13:24:52 +0000

Suppose you want to add 12.96, 3.5 and 8.
Line up the decimal points.
Begin adding from the right-hand column. Treat the blank spaces after 3.5 and 8 as zeroes.
Add first column.
Continue to the left.
Complete the problem column by column, and at the end, put the decimal point directly below the others.

Dividing Integers

admin — Wed, 31 Mar 2010 07:44:24 +0000

Suppose you want to find 45 divided by 3.
Start off by writing the problem like this.
To begin, ask how many times 3 goes into 4 — that is, what’s 4 divided by 3?
The answer is 1 , so write 1 directly above the 4.
Now multiply 1 by 3 to get 3, place the answer directly below the 4, and draw a line beneath it.
Subtract 4 – 3 to get 1.
Then bring down the 5 to make the new number 15.
Now ask how many times 3 goes into 15.
The answer is 5.
Write 5 just above the 5 and then multiply 3 by 5 to get 15; write the answer under 15.
Now subtract 15 – 15 = 0.
Because you have no more numbers to bring down, you’re finished.
So 45 divided by 3 equals 15.

Subtracting Integers

admin — Sun, 28 Mar 2010 13:24:32 +0000

Suppose you want to subtract 83 – 56.
Begin subtracting in the ones column: 3 – 6.
Because 3 is smaller than 6, you need to borrow from the tens column.
Subtract 1 from the 8 replacing 8 with a 7.

Next,add 10 to the 3, changing it to an 13.
Now you can subtract in the ones column: 13 – 6 = 7.
Next, move to the tens column.
Subtract 5 from 7 which gives you 2.
We find that 83-56=27.

Adding Large Numbers in Columns

admin — Mon, 22 Mar 2010 07:43:11 +0000

Suppose we want to add 26 and 79
Stack the numbers one on top of another so that the ones digits line up in a column and the tens digits line up in another column.
Add column by column, starting from the ones column on the right.

First add the ones column:
The sum is a two-digit number so you need to write down the ones digit of that number and carry
the tens digit over to the next column to the left, write this digit above the column so you can add it with the rest of the numbers in that column.
Next, move to the tens column:
Because this is the last column to add we write down the sum, we don’t have to carry.
This problem shows you that 26+79 =105

Multiplying Larger Numbers

admin — Fri, 19 Mar 2010 16:33:55 +0000

Suppose we want to multiply 57 by 13. First we multiply 57 by 3 to get 171 .
Next we multiply 57 by 1..
1 is in the tens column so it really means 10. We have to put a 0 directly under the 1 in 171.
Now we can multiply 57 by 1 to get 57.
To finish up, add the two products
So 57 multiplyed by 13 is 741.

Multiplying Large Numbers

admin — Fri, 05 Mar 2010 15:39:30 +0000

Suppose we want to multiply 45 by 8. Start by stacking these numbers one on top of another with a line underneath. Multiply 8 by 5 . 8 by 5 is 40 so write down the 0 and carry the 4. Next, multiply 8 by 4. 8 by 4 is 32 . We need to add the 4 that we carried over, which makes the result 36. Because 8 and 4 are the last numbers to multiply, we write down the 36, we don’t have to carry. We find that 45 multiplied by 8 is 360.