Solve Multi-Step Problems with Multiplication and Division

Learn how to solve complex problems that require multiple steps using multiplication and division.

Solution: Exercises 1 to 3
1 School Library Books
Exercise 1
The school library has 4 shelves. Each shelf holds 8 books. If 12 books are checked out, how many books are left in the library?
Definition:

Multi-step problem: A problem that requires more than one operation to solve. You must solve one part before moving to the next.

Problem Steps

Step 1: Find the total number of books in the library

Step 2: Subtract the number of books checked out

Solution method:
  1. Identify what needs to be found
  2. Determine the operations needed
  3. Solve step by step
  4. Check your answer
Step 1: Find total books

Shelves = 4, Books per shelf = 8

Total books = 4 × 8 = 32 books

Step 2: Subtract checked out books

Books checked out = 12

Books left = 32 - 12 = 20 books

Step 3: Verify the answer

Books left + Checked out = Total

20 + 12 = 32 ✓

4 × 8 - 12 = 20
Final answer:

There are 20 books left in the library.

Applied rules:

• Order of operations: Multiplication before subtraction

• Multi-step approach: Solve one part at a time

• Verification: Check your answer makes sense

2 Garden Planting Problem
Exercise 2
A gardener plants 24 seeds in 3 equal rows. Later, he adds 5 more seeds to each row. How many seeds are in each row now?
Definition:

Division in multi-step problems: Used to distribute items equally among groups or find the number of items per group.

Problem Steps

Step 1: Find how many seeds were in each row initially

Step 2: Add the additional seeds to each row

Step 1: Find seeds per row initially

Total seeds = 24, Number of rows = 3

Seeds per row = 24 ÷ 3 = 8 seeds per row

Step 2: Add additional seeds

Additional seeds per row = 5

New seeds per row = 8 + 5 = 13 seeds per row

Step 3: Verify the answer

Initial total + Added seeds = New total

(8 × 3) + (5 × 3) = 24 + 15 = 39

New total = 13 × 3 = 39 ✓

24 ÷ 3 + 5 = 13
Final answer:

There are 13 seeds in each row now.

Applied rules:

• Division: Distribute items equally among groups

• Multi-step approach: Solve one calculation before the next

• Verification: Confirm your calculations are correct

3 Clothing Store Problem
Exercise 3
A store has 5 racks with 6 shirts each. They sell 14 shirts and then rearrange the remaining shirts equally on 4 racks. How many shirts are on each rack now?
Definition:

Complex multi-step problem: A problem that requires multiple operations in sequence, often involving both multiplication and division.

Problem Steps

Step 1: Find the initial total number of shirts

Step 2: Subtract the sold shirts

Step 3: Divide the remaining shirts among new racks

Step 1: Find initial total shirts

Racks = 5, Shirts per rack = 6

Initial total = 5 × 6 = 30 shirts

Step 2: Subtract sold shirts

Shirts sold = 14

Remaining shirts = 30 - 14 = 16 shirts

Step 3: Divide among new racks

New racks = 4

Shirts per new rack = 16 ÷ 4 = 4 shirts per rack

Step 4: Verify the answer

Shirts on new racks + Sold shirts = Initial total

(4 × 4) + 14 = 16 + 14 = 30 ✓

(5 × 6 - 14) ÷ 4 = 4
Final answer:

There are 4 shirts on each rack now.

Applied rules:

• Order matters: Solve operations in the correct sequence

• Multiple operations: Use both multiplication and division as needed

• Verification: Always check that your answer is reasonable

Multi-Step Problem Solving Strategies
Operations in Order
Problem Solving Sequence
Multiplication

When to use: finding totals of equal groups

Division

When to use: sharing equally or finding groups

Addition

When to use: combining amounts

Subtraction

When to use: taking away or comparing

🔍
Read Carefully
Identify what you need to find
📝
Plan Steps
Decide what to calculate first
✅
Check Answer
Verify it makes sense
🔢
Order of Operations
Multiplication/
Division first,
then Addition/
Subtraction
🔄
Multiple Steps
Solve one step
at a time
🔍
Key Words
"each", "per",
"total", "shared"
Key Strategy: Break complex problems into smaller parts.
Common Mistake: Forgetting the order of operations.
Tips, Tricks, and Key Notes
Tip 1: Circle or underline key numbers in the problem.
Tip 2: Write down each step as you solve it.
Tip 3: Ask yourself if your answer makes sense.
Tip 4: Draw pictures to visualize the problem.
Tip 5: Check your work by working backwards.
Key Definitions:

Multi-Step Problem: A problem that requires more than one operation to solve

Multiplication: Combining equal groups together

Division: Sharing equally or finding how many groups

Order of Operations: The sequence in which operations are performed

Problem Solving: Using math to find solutions to real-world situations

Verification: Checking that your answer is correct

Important Rules to Remember:

• Solve multi-step problems one step at a time

• Multiplication and division come before addition and subtraction

• Always check if your answer makes sense in the context

• Look for key words that indicate which operation to use

• Draw diagrams when problems are difficult to visualize

Complete Learning Summary: Solving Multi-Step Problems with Multiplication and Division
Comprehensive Learning Summary

Definitions of All Concepts Used

Multi-Step Problem: A mathematical problem that requires more than one operation to solve. You must complete one step before moving to the next.

Multiplication: A mathematical operation that combines equal groups together. It's a shortcut for repeated addition.

Division: A mathematical operation that shares items equally or finds how many groups can be made.

Order of Operations: The sequence in which mathematical operations should be performed: multiplication and division before addition and subtraction.

Problem Solving: The process of using mathematical operations to find solutions to real-world situations.

Verification: The process of checking that your answer is correct and makes sense in the context of the problem.

Core Rules and Principles

Order of Operations: When solving problems with multiple operations, perform multiplication and division before addition and subtraction.

Sequential Approach: Multi-step problems must be solved one step at a time, using the result of each step in the next.

Context Matters: Always consider whether your answer makes sense in the real-world situation described in the problem.

Operation Selection: Choose the correct operation based on what the problem is asking (multiplication for total of groups, division for equal sharing).

Step-by-Step Methods and Procedures

  1. Read the problem carefully: Identify what information is given and what needs to be found
  2. Plan the steps: Decide which operations to perform and in what order
  3. Solve step by step: Complete one calculation at a time
  4. Record each step: Write down your work to avoid mistakes
  5. Check your answer: Verify it makes sense in the context of the problem
  6. Verify calculations: Double-check your arithmetic

Multiple Concrete Examples

Simple Example: 3 boxes with 4 apples each, then eat 5 → 3×4=12, then 12-5=7 apples left

Intermediate Example: 24 students in 4 equal groups, then add 2 to each group → 24÷4=6, then 6+2=8 per group

Advanced Example: 5 shelves with 6 books each, sell 14, redistribute to 4 shelves → (5×6-14)÷4=4 per shelf

Tips, Tricks, and Common Pitfalls

Tips: Underline key numbers; write down each step; draw pictures when needed; check your work

Tricks: "What do I need to find first?" helps determine the order of operations

Common Pitfalls: Forgetting the order of operations; rushing through steps; not checking if the answer makes sense

Key Notes for Memorization

Memory Aid: "Multiply/Divide before Add/Subtract" - think of MD before AS

Formula to Remember: Multi-step problems = One step at a time

Visual Pattern: Break complex problems into smaller, manageable pieces

Quick Reference Guide

Problem Solving Steps

1. Read carefully

2. Plan the steps

3. Solve one at a time

4. Check your answer

Order of Operations

1. Multiplication

2. Division

3. Addition

4. Subtraction

Questions & Answers

Question: How do I know which operation to do first in a multi-step problem?

Answer: Here's how to decide which operation to do first:

  • Read the whole problem first to understand what's happening
  • Look for key words that indicate operations ("each" usually means multiply, "shared equally" means divide)
  • Follow the order of operations: multiplication and division come before addition and subtraction
  • Think about logic: What do you need to find first to solve the next part?

For example, if you have "3 boxes with 4 apples each, then eat 5":

  • You need to know the total apples first (multiply)
  • Then subtract the eaten apples (subtract)

Always solve problems step by step, using the result of one step to help with the next!

Question: My child gets overwhelmed with multi-step problems. How can I help them break them down?

Answer: Here are strategies to help break down multi-step problems:

  • Read together: Have your child read the problem aloud slowly
  • Highlight key information: Circle numbers and underline what's being asked
  • Ask guiding questions: "What happens first?", "What do we need to find next?"
  • Draw a picture: Visualize the situation to make it clearer
  • Solve one step at a time: Don't try to solve everything at once

For example, with "Sarah has 4 boxes with 5 pencils each, gives away 6":

  • Step 1: Find total pencils (4 × 5 = 20)
  • Step 2: Subtract given away (20 - 6 = 14)

Practice with simple problems first, then gradually increase complexity.

Question: What if I get the wrong answer on the first step? Will all my other steps be wrong?

Answer: If you make a mistake in the first step, it will affect your final answer, but that's okay! Here's what to do:

  • Check your work: Go back and review each step if your answer seems wrong
  • Use estimation: Does your answer make sense? If not, check your steps
  • Verify with another method: Try solving differently to confirm
  • Learn from mistakes: Each error teaches you how to do it better next time

For example, if you calculated 4 × 5 = 19 instead of 20 in the first step:

  • Next step would be 19 - 6 = 13 (wrong final answer)
  • Checking: 4 × 5 should equal 20, so restart with correct first step
  • Correct: 20 - 6 = 14

The important thing is to always check your work and learn from errors!