-
@ 638d2a79:f5645f4e
2025-02-05 18:05:19
When doing division with two-digit dividends, round up to the nearest tens place if the number ends in 6-9.
**Example:**
200÷29200 \div 29200÷29 can be approximated as 200÷30200 \div 30200÷30, which simplifies to 20÷320 \div 320÷3.
Also, zeros cancel out in division.
**Example:**
20000÷70020000 \div 70020000÷700 can be simplified to 200÷7200 \div 7200÷7, which gives the same answer.
### Multiplication Rule:
When doing multiplication, do not write out all of the zeros.
**Example:**
For 90×290 \times 290×2, you don’t need to write out “00” at the start. Just do 9×29 \times 29×2 and add the zero later.
### Division with Two-Digit Divisors:
If the second digit of the divisor is between 1-5, only divide the first digit by the first digit.
**Example:**
5124÷215124 \div 215124÷21 can be solved as follows:
1. Approximate: 5÷2=25 \div 2 = 25÷2=2 (write 2 as the first digit).
2. 21×2=4221 \times 2 = 4221×2=42, subtract to get 92.
3. 9÷2≈49 \div 2 \approx 49÷2≈4, so 21×4=8421 \times 4 = 8421×4=84, subtract to get 8.
4. Bring down the 4 to make 84, which we already know is 21×421 \times 421×4.
5. Final answer: **244**.
![[Recording 20250122112454.m4a]]
### Converting a Remainder into a Decimal:
To turn a remainder into a decimal, divide the remainder by the divisor.
6. Add a zero to the end of your remainder and divide normally.
7. The quotient becomes the decimal value.
**Example:**
32÷10032 \div 10032÷100 → Rewrite as 320÷100320 \div 100320÷100.
- 100 goes into 320 three times (3).
- Bring down a zero → 30.
- Add another zero → 300 → 100 goes in three times (3).
- Final answer: **0.32**.
If one of the numbers is smaller, like in 880÷22880 \div 22880÷22, where 22 doesn’t go into 0:
- Instead, check how many times **0.22** goes into **88**. The answer is **4**.
- 22 goes into 0, 0 times.
- So, 880÷22=40880 \div 22 = 40880÷22=40.
### Division with Three-Digit Numbers:
Use the same method as with two-digit divisors.
**Example:** 100,492÷518100,492 \div 518100,492÷518
- Approximate using **5** for each digit of the answer.
Another example:
36.85÷21636.85 \div 21636.85÷216
- 222 goes into **3** once → Write **1**.
- 216×1=216216 \times 1 = 216216×1=216, subtract from **368** → **152**.
- Bring down the **5** and continue dividing.
### Calculating Volume:
To find the volume of something, use the equation:
Width×Height\text{Width} \times \text{Height}Width×Height
The answer will be in **square units**.
**Example:**
A 2D box with width **1 inch** and height **4 inches** has an area of **4 inches squared**.
### [[America|American]] Flag Instructions:
- The length of the flag is **1.9 times its width**.
- Each stripe should be **one-thirteenth** of the flag's height.
- The blue area covers **7.6** of the flag’s width.
- The height of the blue area is exactly **7 stripes**, or **7/13** of the flag’s height.
### Finding the Median Score of a Class:
8. Count the number of students with the highest score, then move downward.
9. Write scores in one column and the number of students in another.
10. Find the median of the possible scores.
**Example:**
Possible scores: **10, 9, 8, 6, 4** → Median is **8**.
Then, count students until you reach the middle score **(8 or the median value)**
| Posable score | number of students |
| - | |
| 10 | 3 |
| 9 | 6 |
| 8 | 4 |
| 6 | 1 |
| 4 | 1 |
The answer would be 6 1,2,3,4,5,6,7,8 and we are in the 6 Groupe
Tags: [[arrhythmic]]