Fill in the missing number.30% of = 21

To find the missing number, you need to follow these steps:

1. Understand that "30% of _ = 21" means you need to find a number that when you take 30% of it, you get 21.

2. To do this, you can set up the equation like this: 0.30 * x = 21, where x is the missing number.

3. To solve for x, you can divide both sides of the equation by 0.30.

4. So, x = 21 / 0.30

5. If you do the division, you find that x = 70.

So, the missing number is 70.