Stack It Up: Column Addition

Imagine you have 36 stickers and your friend gives you 47 more. How would you work out the total? You could count on your fingers, but what if the numbers were really big? Today you will learn a method that works for ANY numbers — column addition. Before we start, try this: what is 6 + 7? Hold that answer in your head — you will need it soon!

Column addition is a way of setting out numbers in rows so you can add them step by step. You line the numbers up so that the ones digits are in the same column and the tens digits are in the same column. Here is the big rule: always start from the ones column (the column on the right) and work left. Sometimes when you add the ones, you get a number that is 10 or more. When that happens, you write the ones digit of your answer below the line, and you carry the ten into the tens column by writing a small 1 underneath the tens column. This small 1 is called the carry. Let's walk through 36 + 47 together. Step 1 — Write the numbers in columns: 3 6 + 4 7 ——— Step 2 — Add the ones: 6 + 7 = 13. Write 3 in the ones place below the line. Carry the 1 ten into the tens column. 3 6 + 4 7 ——— 3 (and carry 1) Step 3 — Add the tens: 3 + 4 = 7, then add the carried 1: 7 + 1 = 8. Write 8 in the tens place. 3 6 + 4 7 ——— 8 3 So 36 + 47 = 83.