Question

The predecessor of a two digit number is never a single digit number. Is that statement true or false?

Answer 1

Hint: The smallest two digit number is 10 and the largest two digit number is 99. Now, the predecessor of a number is the number which is one less than the given number. For e.g. if we have to find the predecessor of say 15 then one less than 15 is 14 so the predecessor of 15 is 14. Similarly, find the numbers one less than 10 and 99 and see whether we are getting a single digit or not.

Complete step by step answer:
We have to state true or false for the following statement given in the above question:
The predecessor of a two digit number is never a single digit number
Now, to comment on this statement we should first know what a predecessor means. So, a predecessor of a number is the number which is one less than the given number. For e.g. if my number is 100 then the predecessor of 100 is one less than 100 and one less than 100 is 99.
In the above question, we have to comment upon the predecessor of a two digit number. We know that the smallest two digit number is 10 and the largest two digit number is 99 so if we find the predecessors of these numbers then we are in a good position to comment.
The predecessor of 10 is subtracting 1 from 10 which is equal to 9.
And the predecessor of 99 is subtracting 1 from 99 which is equal to 98.
The question is asking whether the predecessor of a two digit number is never a single digit number as you can see from the above predecessors of the two numbers 10 and 99 you will find that the predecessor of 10 is 9 which is a single digit number. Hence, we have got a two digit number whose predecessor is a single digit.

Hence, the statement given in the above problem is false.

Note: You might think that we can also check the predecessors of the two digit numbers written between 10 and 99. The answer is yes, you can check the predecessors of the two digit numbers for your satisfaction but in falsifying a statement one argument is enough to falsify it that we have shown above showing the predecessor of number 10 as a single digit.