Dana wants to find the sum
3 4 6
4 2 1
+1 5 2
________
We will not regroup this ones place because the sum of the digits in the ones place is not up to. It's just 6+1+2 = 9.
Therefore, 13a) No.
There is no regrouped tens to add, so we would not able to regroup the ones place.
Therefore, 13b) No.
We regroup the tens place because the sum of the digits in the ones place is upto to 10.
And 13c) Yes.
We add the regrouped hundred as we regrouped the ones place.
Therefore,
13 D) Yes.
There are 720 ways through which 3 numbers can be selected from 10 numbers to open a keypad lock.
Given that there are 10 numbers are 3 numbers are required to open a keypad lock.
Permutations are the number of ways in which objects can be selected without replacements to form subsets.
It is expressed as n=n!/(n-r)!.
Factorial of a number is the product of consecutive numbers less than the number.
Total numbers available=10
Numbers to be selected=3
Number of ways can be found by using permutations.
Number of ways =10
=10!/(10-3)!
=10!/7!
=10*9*8*7!/7!
=10*9*8
=720 ways.
Hence there are 720 ways through which 3 numbers can be selected from 10 numbers.
Learn more about permutations at brainly.com/question/1216161
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