Question

When is 9+10 really equal to 21

Answer 1

It can never be equal to 21 because that’s not how math works

Answer 2

9 + 10 = 21

Explanation:

9 + 10 = 21

Factor out 9 and 10

9 = 3 · 3 10 = 2 · 5

Next multiply 3 by 2

3 × 2 = 6

Then multiply 3 by 5

3 · 5 = 15

Finally add the products

15 + 6 = 21