Question

1+4=5 2+5=12 3+6=21 puzzle

Answer 1

They also add the previous sum....1+4=5 and 5+5+2 is 12....12+6+3 is 21 and so on (:

Answer 2

The puzzle is first add the current two numbers and then add their sum to result obtained in previous step.

Explanation:

1 + 4 = 5

2 + 5 = 12

12 is obtained by adding 2 + 5 = 7 and adding the result obtained in previous result which is 5 to 7

⇒ 7 + 5 = 12

Now, 3 + 6 = 21

21 is obtained by first adding 3 + 6 = 9 and the previous result obtained is 12

So adding 12 to 9 ⇒ 12 + 9 = 21

Hence, The puzzle is first add the current two numbers and then add their sum to result obtained in previous step.