## Seive of Eratosthenes

#### September 26, 2011 by Tracy Watanabe · No Comments · Learning, Math

I will be telling you how to figure out how to do the Sieve of Eratosthenes and that will help you to figure out the prime and composite numbers in between 1 and a 100.

The first step is to make a circle around the number 2.

The second step is to start on the number 4 skip count by 2s till 100 and make an x on every number.

The third step is to circle the number three.

The forth step is to start on the number 6 skip count by 3s till 100 and make an x on every number.

The fifth step is to circle the number 5.

The sixth step is to start on the number 10 skip count by 5s till 100 and make an x on every number

The seventh step is to circle the number 7.

The eighth step is to start on the number 14 skip count by 7s till 100 and make an x on every number.

If you do this. These will be your prime numbers: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 71, 73, 79, 83, 89, and 97.

Here’s a link that will bring you to a Seive of Eratosthenes that goes from 2 to 400.

## Math Lattice Method

#### September 7, 2011 by Tracy Watanabe · 2 Comments · Learning, Math

In math there are different ways to solve problems. The lattice method is an example of another way to do multiplication. I think it is easier.

Step 1:

If you need help on a multiplication problem like 567 times 432 make a three by three grid.

Step 2:

Then Draw a line in every box  from the top right to the bottom left corner.

Step 3:

On  the top and side write down the multiplication problem.

Step 4:

In each box you will need to multiply the number that is above it and to the side of it.

Step 5:

Now you will need to draw lines diagonally from the grid.

Step 6:

Finally, you will need to add up the line that is diagonally, and then you will get the answer.

If you follow these steps you can easily finish a multiplication problem. You can do this on any multiplication problem.