Addition: fill in the missing digits

Key notes:

✨ Key Points:

1. Addition means putting numbers together to find the total.

2. Sometimes, in addition problems, one or more digits are missing.

3. To solve, we look carefully at the place values – ones, tens, hundreds.

4. Always add from right to left (ones → tens → hundreds).

5. Use carrying (regrouping) if the sum of a column is 10 or more.

6. Fill in the missing digit by thinking backwards:

  • If a number is missing in the addition, check the column total.
  • Subtract to find the missing digit.
🧮 Example Problems:

1. Without Carrying

   3 5
+  2 _
------
   5 7
  • 👉 In the ones place: 5 + _ = 7 → missing digit = 2

Answer:

   3 5
+  2 2
------
   5 7

2. With Carrying

   4 _
+  2 8
------
   7 3
  • 👉 In the ones place: _ + 8 = 3 (carry 1).
  • So, missing digit = 5.

Answer:

   4 5
+  2 8
------
   7 3
🔑 Steps to Remember:
  • Start with the ones place.
  • Check if carrying is needed.
  • Subtract to find the missing digit.
  • Move to the next column.
  • Double-check your work. ✅
✍️ Practice Questions:
   2 _
+  3 4
------
   6 8

   _ 7
+  2 8
------
   5 5

   4 2
+  _ 9
------
   7 1

Learn with an example

➡️ Type the missing digit:

Start on the right. Add the ones column, remembering to carry over. Look at the tens column. The tens column must add up to 6. The missing number is 4.

➡️ Type the missing digit:

Start on the right. Add the ones column. Look at the tens column. The tens column must add up to 7. The missing number is 5.

➡️ Type the missing digit:

Start on the right. Look at the ones column. Add the ones. The missing number is 5.

Let’s practice!