Four columns: thousands, hundreds, tens, ones. Line them up, one digit per square, and start from the ones as always. The rule does not change with the size.
Step 1: Let's Learn
Read it, or press Listen and follow the words.
Carry after carry
2,648 + 1,975. Ones: 8 + 5 = 13, write 3 carry 1. Tens: 4 + 7 + 1 = 12, write 2 carry 1. Hundreds: 6 + 9 + 1 = 16, write 6 carry 1. Thousands: 2 + 1 + 1 = 4. The answer is 4,623.
A carry past the front
7,859 + 4,386. The thousands make 7 + 4 + 1 = 12. There is no column to the left, so write both digits: 12. The answer is 12,245, a five-digit number.
The comma
A comma every three digits from the right makes 12,245 readable. It does not change the columns; write the digits one per square and add the comma when you read the answer.
Estimate to check
2,648 + 1,975 is about 2,600 + 2,000 = 4,600. 7,859 + 4,386 is about 8,000 + 4,000 = 12,000. An answer far from the estimate means a column slipped.
Step 2: Try It Yourself
Press Next step. Three carries, then a fourth column.
2648+1975
2,648 and 1,975 as pieces
Step 0 of 4
2,648 + 1,975 = …
11117859+438612245
7,859 + 4,386 = 12,245
- 1Ones: 9 + 6 = 15. Write 5, carry 1 to the tens.
- 2Tens: 5 + 8 + the carried 1 = 14. Write 4, carry 1 to the hundreds.
- 3Hundreds: 8 + 3 + the carried 1 = 12. Write 2, carry 1 to the thousands.
- 4Thousands: 7 + 4 + the carried 1 = 12. Write 2, carry 1 to the ten thousands.
- 5Ten thousands: only the carried 1. Write 1. 7,859 + 4,386 = 12,245.
Step 3: In Real Life
A town’s two schools
One school has 2,648 pupils, the other 1,975. The council adds them in columns: 8 + 5 = 13, 4 + 7 + 1 = 12, 6 + 9 + 1 = 16, 2 + 1 + 1 = 4. 4,623 pupils, carried three times.
Step 4: Watch an Example
One step at a time.
Watch Priya Add 3,456 and 2,789
Priya writes 3,456 above 2,789, one digit per square.
- Step 1
Ones: 6 + 9 = 15. She writes 5, carries 1.
Step 5: Your Turn
Practice makes it stick.
The Two Schools
Problem 1 of 2
2,648 pupils and 1,975 pupils. How many altogether?
pupils
The Charity Run
Problem 2 of 2
7,859 dollars raised on Saturday and 4,386 on Sunday. Total in dollars?
dollars
Four Columns
1 of 4
3,456 + 2,789
2 of 4
7,859 + 4,386
3 of 4
5,072 + 3,948
4 of 4
9,999 + 1
Step 6: Quick Check
Show what you know.
Question 1 of 2
2,648 + 1,975
Question 2 of 2
The thousands column makes 12 and there is no column to the left. What do you write?
What You Learned
- Four columns, the same rule: ones first.
- Carry in as many columns as needed.
- A carry past the front is the answer’s new first digit.
For the grown-up
This is lesson 1.5 written out. Nothing new happens at four digits except that carries pile up; a child who is unsure should say each column aloud, including the carry, before writing.
Insist on squared paper or a ruled grid. Most four-digit errors are a digit in the wrong column, not a wrong sum.