This type of question is most commonly asked in exams. In it, a word is given and candidates are asked to find out the number of pairs of letters that matches the same sequence as in the English Alphabets.
Example: How many such pairs of letters are there in the word PROTEST each of which has as many letters in the same sequence between them in the word as in the English alphabets?
In many books, it is said that the difficulty level of this type of question is easy. But I didn’t get a single one to explain how to solve it or that I got is brain shaking one.
Suppose, the word given is “PROTEST”.
Step 1: First write down numeric code of each alphabet (as it is in the alphabets) under each alphabet respectively. In this case, for P we have 16, similarly R => 18, O=>15, T=>20, E=>5, S=>19 and T=>20.
Step 2: Take the code of first letter of the word from the left as base, start counting and reach the last letter. In between, find what number is matched with number written in Step 1. Each match will be a required pair.
Note: Comparison in every step will be respect to the Step 1.
Step 3: Continue the same process with other letters as in step 2.
Step 4: When left to right counting approach is complete we need to do the same reversely, i.e. this time start counting from the right.
Note: During counting consecutive numbers from the base, we can reach upto 26 (as number of alphabets is 26) and then next number will start form 1.
In this case, from left to right move base is 16 and from right to left move it is 20.