When you add numbers, the result is called the *sum*, and the numbers you add are called *addends*. Addition is shown using the plus sign (+). You can use a number line to help visualize addition by moving right to represent each addend. **Example:** To add 2 and 3, start at zero on the number line. Move right 2 spaces to reach 2, then move 3 more spaces to reach 5. So, $(2 + 3 = 5)$. **Rules of Addition:** 1. **Commutative Law**: You can add numbers in any order, and the sum will be the same. For example, $(5 + 3 = 8)$ and $(3 + 5 = 8)$. 2. **Associative Law**: When adding multiple numbers, you can group them in any order. For example, $((3 + 5) + 7 = 15)$ and $(3 + (5 + 7) = 15)$. When adding several numbers, it’s easiest to line them up in columns by place value (units, tens, hundreds, etc.). Start with the units column and move left, carrying over numbers if needed. **Example:** To add 345, 25, 1458, and 6: - Write them in a column. - Add units first: $(5 + 5 + 8 + 6 = 24)$. Write 4 and carry over 2. - Add tens: $(2 + 4 + 2 + 5 = 13)$. Write 3 and carry over 1. - Add hundreds: $(1 + 3 + 4 = 8)$. The sum is 1834. To double-check, add from the bottom to the top.