Adding Zero & One (Counting On)

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What happens when you add $0$ to any number?

When you add $0$ to any number, the number stays the same. This is because you are adding nothing to it.

$$ 5 + 0 = ? $$

$$ 5 + 0 = 5 $$

$$ 0 + 8 = ? $$

$$ 0 + 8 = 8 $$

$$ 9 + 0 = ? $$

$$ 9 + 0 = 9 $$

$$ 1 + 0 = ? $$

$$ 1 + 0 = 1 $$

What is a fast way to add $1$ to any number?

Just say the next number when you count. This is called 'counting on'.

How do you solve $6 + 1$ by counting on?

You start at $6$ and count on one more number, which is $7$. So, $6 + 1 = 7$.

$$ 4 + 1 = ? $$

$$ 4 + 1 = 5 $$

$$ 1 + 7 = ? $$

$$ 1 + 7 = 8 $$

$$ 8 + 1 = ? $$

$$ 8 + 1 = 9 $$

$$ 2 + 1 = ? $$

$$ 2 + 1 = 3 $$

$$ 1 + 5 = ? $$

$$ 1 + 5 = 6 $$

The rule that says adding $0$ doesn't change a number is called the 'Identity Property of Addition'. What is $7 + 0$?

$7$. The number stays the same.

$$ 0 + 0 = ? $$

$$ 0 + 0 = 0 $$