Definition:

Three-digit addition involves combining two or more numbers, each with three digits. This process is done by adding the values in the ones, tens, and hundreds of places, starting from the right (one's place) and moving to the left. If the sum in any place value exceeds 9, a carry is added to the next higher place value.

Example 1:

Add 376 and 482.

Solution:

• Align the numbers by place value. 376+482.
• Add from right to left:
• One place: 6+2=8
• Tens place: 7+8=15. Write 5, carry over 1.
• Hundreds place 3+4 = 7, plus the carryover 1 = 8.

Final solution: 376+482=858.

Example 2:

Add 245 and 378.

Solution:

• Align the numbers by place value: 245+378
•  Add from right to left:
• One place: 5+8=13, carry over 1.
• Tens place: 4+7=11, plus the carryover 1=12. Write 2, carry over 1.
• Hundreds place 2+3=5, plus the carryover 1=6.

Final solution:245+378=623

Example 3:

Add 208 and 9.

Solution:

• Write the numbers in column form: 208 + 9
• Add the ones in place: 8+9=17 (write 7, carry over 1 to the tens place.)
• Add the tens place: 0+1=1
• Add the hundreds place:2+0=2

Final solution: 208+9=217

Example 3:

Add 603 and 8.

Solution:

• Write the numbers in column form: 603 + 8
• Add the ones in place: 3+8=11 (write 1, carry over 1 to the tens place)
• Add the tens place: 0+1=1
• Add the hundreds place:6+0=6

Final solution: 603+8=611

Example 5:

Add 456 and 289.

Solution:

• Add the one's place: 6+9=15. Write down 5 and carry over 1 to the tens place.
• Add the tens place: 5+8 = 13, then add the carryover: 13+1 = 14. Write down 4 and carry over 1 to the hundreds place.
• Add the hundreds place: 4+2=6, then add the carryover: 6+1=7.

Final solution: 456+289=745.

Why it matters:

Adding 3-digit numbers is a fundamental math skill that helps solve everyday problems, from calculating expenses to measuring quantities. It builds a strong foundation for advanced arithmetic concepts like multiplication and division. Mastering addition improves problem-solving, logical thinking, and mental math abilities.

By practicing addition with 3-digit numbers, you can solve real-world problems quickly!

Let’s practice and evaluate your work together by adding 3-digit numbers.