Calculate Total Cost: Multiplying $1.50 × 100 for Class Supplies

Q: What if I forget that 'a dollar and a half' means $1.50?

Break it down: 'a dollar' = $1.00 and 'a half' = $0.50. Add them together: $1.00 + $0.50 = $1.50. This phrase always means $1.50!

Q: Can I solve this problem a different way?

Yes! You could think of it as 100 groups of $1.50 each. Or break it into: (100 × $1) + (100 × $0.50) = $100 + $50 = $150. Same answer!

Q: How do I know my answer is reasonable?

Use estimation: 100 packs at about $1.50 each should cost around $150. Since chip packages usually cost $1-$2, spending $150 for 100 packs makes perfect sense!

Q: What if the problem used different numbers?

The same method works: cost per item × number of items = total cost. Whether it's $2.25 × 50 students or $0.75 × 200 students, just multiply directly!

Decimal Multiplication with Large Whole Numbers

A package of potato chips costs a dollar and a half. A teacher bought enough packs for 100 students to have one each. How much did she pay in total?

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Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

A package of potato chips costs a dollar and a half. A teacher bought enough packs for 100 students to have one each. How much did she pay in total?

Step-by-step solution

To solve this problem, we'll use straightforward multiplication:

Step 1: Determine the cost per pack, which is $1.5$ dollars.
Step 2: Determine the number of packs needed, which equals the number of students: $100$ .
Step 3: Multiply the cost per pack by the number of packs:

$\text{Total Cost} = 1.5 \times 100$

$\text{Total Cost} = 150$ dollars

Therefore, the total amount paid by the teacher is $150$ dollars.

Final Answer

$150$ $

Key Points to Remember

Essential concepts to master this topic

Rule: Multiply decimal by whole number using standard multiplication
Technique: $1.5 \times 100 = 150$ by moving decimal two places right
Check: Verify units make sense: 100 packs at $1.50 each = $150 ✓

Common Mistakes

Avoid these frequent errors

Converting decimal incorrectly or misplacing decimal point
Don't think 1.5 × 100 = 15 by ignoring the decimal placement! This gives an answer 10 times too small because you're treating 1.5 as 15 hundredths instead of 1 and 5 tenths. Always remember that multiplying by 100 moves the decimal point two places to the right.

Practice Quiz

Test your knowledge with interactive questions

$0.26\times10=$

FAQ

Everything you need to know about this question

Why does multiplying by 100 move the decimal point two places?

Each zero in 100 represents one decimal place movement. Since 100 has two zeros, the decimal point moves two places to the right. So $1.5 \times 100 = 150$ .

What if I forget that 'a dollar and a half' means $1.50?

Break it down: 'a dollar' = $1.00 and 'a half' = $0.50. Add them together: $1.00 + $0.50 = $1.50. This phrase always means $1.50!

Can I solve this problem a different way?

Yes! You could think of it as 100 groups of $1.50 each. Or break it into: (100 × $1) + (100 × $0.50) = $100 + $50 = $150. Same answer!

How do I know my answer is reasonable?

Use estimation: 100 packs at about $1.50 each should cost around $150. Since chip packages usually cost $1-$2, spending $150 for 100 packs makes perfect sense!

What if the problem used different numbers?

The same method works: cost per item × number of items = total cost. Whether it's $2.25 × 50 students or $0.75 × 200 students, just multiply directly!

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