By adding the correspondent place values of each number, we can see that:
20 + 63 = 83.
The general approach to do mental math is finding patterns.
In this case, we have the sum of:
20 and 63
What you want to do is add the correspondent place values for each number, this is, add the units together and the tens together, in that way you get:
0 + 3 = 3
2 + 6 = 8
Then the sum just gives:
20 + 63 = 83
If you want to earn more about place values, you can read:
https://brainly.com/question/12386995
