Real-world examples of multiplying by 4 with Double the Double.

📚 Quick Study Guide

• 🔢 Multiplying by 4 is the same as doubling a number and then doubling it again.
• 💡 This method is called "double the double."
• ➕ Example: To calculate $6 \times 4$, first double 6 to get 12, then double 12 to get 24. Therefore, $6 \times 4 = 24$.
• ✔️ This works because $4 = 2 \times 2$, so multiplying by 4 is the same as multiplying by 2 twice.
• ✍️ Formula: $x \times 4 = (x \times 2) \times 2$

Practice Quiz

1. Question 1: A baker needs to bake 4 cakes for a party. Each cake requires 7 eggs. Using the 'double the double' method, how many eggs does the baker need in total?
   1. 14
   2. 21
   3. 28
   4. 35
2. Question 2: A student reads 9 pages of a book each day. How many pages does the student read in 4 days using 'double the double'?
   1. 18
   2. 27
   3. 36
   4. 45
3. Question 3: A farmer plants 5 rows of apple trees, with 4 trees in each row. How many apple trees are there in total, applying 'double the double'?
   1. 10
   2. 15
   3. 20
   4. 25
4. Question 4: A box contains 12 chocolates. If you buy 4 boxes, how many chocolates do you have in total using 'double the double'?
   1. 24
   2. 36
   3. 48
   4. 60
5. Question 5: A train travels 15 miles per hour. How far does it travel in 4 hours, calculated using 'double the double'?
   1. 30
   2. 45
   3. 60
   4. 75
6. Question 6: Sarah earns $8 per hour. How much does she earn in 4 hours using 'double the double' method?
   1. $16
   2. $24
   3. $32
   4. $40
7. Question 7: A recipe calls for 6 ounces of flour per cake. If you want to bake 4 cakes, how many ounces of flour do you need in total, using 'double the double'?
   1. 12
   2. 18
   3. 24
   4. 30