If we know an integer is a multiple of 5, how many possibilities are there for the last two digits of the integer?
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
Kudos for using Latex to type up the math.
As a note, you needed type it as "\times" in order for it to display as × . Typing "times" simply gives t i m e s . In a sense, the backslash is code for "Change the upcoming command into a mathematical symbol". I've edited your equation so that it displays properly.
This is like an Arithmetic Progression.
The sets of numbers are:
00, 05, 10, 15 and so on till 95 because what we need are the las two digits.
Hence:
a 1 which is the first term of the AP = 0
a n which is the last term of the AP = 95 = a 1 + ( n − 1 ) × d where d is the common difference of 5.
Implies:
95 = 0 + (n-1)d = ( n − 1 ) × 5
5 9 5 = n-1
19 = n-1
n =20 = No. of Possibilties
Too much proness.
Super thinking pattern
Nicely done, but could be done simpler.
see we have to fill 2 places _ _
we can fill the first place means the tens place with 10 digits ( from 0 to 9) So, we have 10 possibilities to fill the 10's place.
And we can fill the ones place only with 0 or 5 as according to the divisibility rule of 5 ones place must be 0 or 5 . so we have only 2 possibilities for ones place.
so total possibilities are 10x2=20
00, 05,10,15,20,25,30,35,40,45,50,55,60,65,70,75,80,85,90,95= 20 Possibilities
The last number of the multiple of 5 must be 0 or 5. we have 0 to 9 number. We can take it 10 times.. 10times2=20 possibilities
If the number is divisible by 5 the last digit should be 0 or 5. Anyway they ask for the last 2 digits.There are 10 one digit numbers (0,1,2,3,4,5,6,7,8,9).All these numbers can be the one before the last digit.All the numbers can go with 2 possible last digits namely 0 & 5.
So,
✳ 10 ✖ 2 = 20
at second last digit 10 options at last only 2 as 0 and 5 so total 10*2=20
The divisibility test of 5 is whether it ends with 0 or 5.If it ends with 0 or 5, it has 5 as a factor. For the second last digit, it can be any digit (0,1,2,3,4,5,6,7,8,9). There are 2 cases for the last digit and 10 cases for the second last digit,so 2 × 1 0 =10= the answer.
QED
The number could end with 0 or 5. The second-to-last digit doesn't affect divisibility by 5, since 10 is a multiple of 5, so it can be any of the 10 digits. The answer is 2 ⋅ 1 0 = 2 0 .
If the integer is divisible by 5, then the units digit must be 0 or 5. If we are looking for the last two digits of an integer that is divisible by 5, then the tens digit can any be number from 0 to 9. Therefore, the total number of possibilities is 10 x 2 which is 20.
All multiples of 5 must end in 0, or 5. The second to last digit can be anything. So we have 10*2=20
We know that a number is divisible by 5 iff - the last digit is either 0 or 5 .
Therefore we have to choose for two spaces :
A B
Now for box A : We have 1 0 possibilities : 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9
And for box B : We have 2 possibilities : 0 , 5
Thus possibilities can be written as :
1 0 2
Therefore total number of possibilities are : 1 0 ⋅ 2 = 1 2 0
Typo in the last answer - 2 0
Lame error- 1 0 × 2 = 2 0 and not 1 2 0 . :P
Problem Loading...
Note Loading...
Set Loading...
For a number to be divisible by 5, the last digit must be 0 or 5. Thus we have two options.
For the digit before the last digit, we can choose from 0 to 9. As long as the last digit is 0 or 5. We have 10 options...
Therefore
10 × 2 = 20 possibilities