Question

Find the missing number in the given pattern:
$\begin{array}{rl}& 1+2=21\\ & 2+3=36\\ & 3+4=43\\ & 4+5=?\end{array}$

Answer 1

Hint: First we are going to analyse the given numbers and try to find out some pattern so that we can find the missing number and we will also describe the pattern so that there is no problem in understanding.

Complete step-by-step answer:
We can see that the odd terms are just writing the number that we write the number in the reverse order of their addition.
Like in the 1st term 1+2 = 21
Here we have written the numbers that are being added in reverse order which is 21.
Now for the 3rd term we get the answer by using the same logic.
So, from this we can deduce that the odd terms follow this pattern.
Now for the even terms we will do the same but in the end the number that we got we will add 4 in it to get the final answer.
Let’s look at the 2nd term,
2+3 now we will write this in reverse order and we get 32 and now as we will add 4 to this number to get the final answer,
Therefore, 32+4 = 36
Hence this is the correct answer.
So, 4+5 is the 4th term which even so it’s answer will be 54+4 = 58.
Hence the missing number is 58.

Note: We have analysed these 3 terms and then we have found some patterns, the method that we have used is very important as one needs to analyse each and every meaning of the numbers. One might get confused about how 1+2 = 21. But in this question 1 and 2 are not numbers but symbols with that in mind we should solve this.