__:__

**Estimation**__Strategy 1:__

__Front-End estimation__: THe digit in the highest place value remains the same. All the other numbers in smaller place values become zeros.

__Strategy 2__:

__Rounding (Close-to Estimation):__Look for a number that is easy to work with, but close to the original number. Rounding to the greatest or second greatest place value is usually the most helpful. This will get you closest to the correct answer.

**Rounding:****Here's the general rule for rounding:**

- If the number you are rounding is followed by 5, 6, 7, 8, or 9, round the number up. Example: 38 rounded to the nearest ten is 40. ...
- If the number you are rounding is followed by 0, 1, 2, 3, or 4, round the number down. Example: 33 rounded to the nearest ten is 30

**Rounding Rules:**Only look to the RIGHT of the place you are rounding.

__Any number to the left will remain the same.__

**0,1,2,3,4 -> the # you are rounding stays the same.**

**5,6,7,8,9 --> the # you are rounding bumps to the next number.**

__Once you round, the rest of the numbers become zeros!__

4 and below, let it go!

5 and above, give it a shove!

Round to the nearest 1,000.

**1**

__8__,234 -->18,000(the two "tells" the 8 to "stay the same" and then the two and the rest of the numbers become zeros. The 1 in the ten-thousands place remains unchanged!

View the place value chart below to help you with your HW and activities.

Remember as you move from a lower value to the next higher value, you are X10.

Example:

__Place Value:__View the place value chart below to help you with your HW and activities.

Remember as you move from a lower value to the next higher value, you are X10.

Example:

__4__0__4__00 The 4 in 400 is 10x the value of the 4 in 40.

__00 The 6 in 6000 is 10x the value of the 6 in 600.__

**6**__000__

**6**Place Value Video

**F O I L**

**Algorithm for solving 2-digit by 2-digit multiplication**F - FIRST

O- OUTER Remember this is the same as the Bowtie, partial products method

I - INNER

L- LAST

**Algorithm:**

**STEP 1**nm * st = total product

**STEP 2**(n + m) * (s + t)

**STEP 3**find the partial products:

__First__n * s = pp1 (the

*number in each parentheses)*

**first**__Outer__n * t = pp2 (the

*number of both parentheses)*

**outer**__Inner__m * s= pp3 (the

*number of both parentheses)*

**inner**__Last__m * t = pp4 (the

*number in each parentheses)*

**last****STEP 4**find the sum of the partial products

____________________________________________

example:

Step 1: 25 * 68 = total product

Step 2: (20 + 5) * (60 + 8) = total product

Step 3:Partials F- 20 * 60 = 1200

O- 20 * 8 = 160

I - 5 * 60 = 300

L- 5 * 8 = 40

Step 4: Sum of partials: 1200 + 160 + 300 + 40 = 1700

So, 25 * 68 = 1700