Addition input/output tables – up to three digits

Ket notes:

What is an Input/Output Table?

• An Input/Output Table is a chart used to show a rule or pattern between numbers.
• The input is the number we start with.
• The output is the result after we apply a rule to the input.
• In this lesson, the rule is addition.

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➕ Focus: Addition of Numbers Up to Three Digits

• We will use three-digit numbers (like 145, 298, 470).
• The same number is added to each input to get the output.

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🧠 How Does It Work?

🔹 Example 1:

Let’s say the rule is “Add 3”.

Input	Rule	Output
125	+3	128
250	+3	253
400	+3	403

🔹 Example 2:

Let’s say the rule is “Add 50”.

Input	Rule	Output
150	+50	200
225	+50	275
390	+50	440

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📝 Steps to Solve Input/Output Tables:

1. Look at the input and output.
2. Figure out what number is added (the rule).
3. Apply the rule to other inputs to find the outputs.
4. Use column addition if needed (hundreds, tens, ones).

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🎯 Practice Questions:

🔹 Find the rule and fill in the output:

Input	Output
100	125
200	225
300	______
400	______

➡ What’s the rule? Add 25

🔹 Use the rule “Add 70” and complete the table:

Input	Output
110	______
230	______
320	______

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🧩 Challenge Table (Find the Input or Output):

Input	Rule	Output
____	+40	185
122	+40	______
199	+40	______

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📚 Real-Life Connection:

• Counting money: If you save ₹100 each month, how much will you have in 3 months?
• Distance: Add kilometers travelled over days.
• Time: Add minutes or hours to a starting time.

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✅ Quick Tips:

• Always align digits by place value when adding.
• Check your addition by reversing: Subtract output – rule = input.
• Use mental math for simple additions like +5, +10, +50.

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🧮 Homework:

1. Create your own input/output table using “Add 45”.
2. Complete the missing numbers:

Input	Output
123	______
300	______
476	______

Learn with an example

Let’s practice!