Subject :IMO Class : Class 3

Class : Class 3

Using Factorial for Class 3 seems difficult.
I taught my daughter as under:-
Step 1 - Put 7 at thousand place and how many different numbers we can get --She replied 6
Step 2- Put 5 at thousand place and how many different numbers we can get --She replied 6
Step 3 -Put 0 at thousand place , do we get four digit number --She replied NO
Ste 4 - Put 2 at thousand place and how many different numbers we can get --She replied 6
Step 5 - Add numbers obtained in above steps we get 18

Class : Class 3

n!-(n-1)! is the answer. n is number of digits here. (n-1)! is subtracted from n! since there is digit with 0. otherwise it is just n!
Now How do you calculate n!. For example 4! here.
4! = 4x3x2x1 = 24
(4-1)! = 3! = 3x2x1 = 6
Hence the answer is n! - (n-1)! = 4! - (4-1)! = 4! - 3! = 24 -6 = 18
Option D is the answer.

Subject :IMO Class : Class 3

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Subject :IMO Class : Class 5

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Subject :IMO Class : Class 6

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Subject :IMO Class : Class 7

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Subject :IMO Class : Class 4

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Subject :IMO Class : Class 4

## Ans 2:

Class : Class 6

It is B %100 sure 23+32=53=5.5
Even if it is confusing the answer is B itself.

## Ans 3:

Class : Class 6

It is B %100 sure 23+32=53=5.5
Even if it is confusing the answer is B itself.

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Subject :IMO Class : Class 5

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Subject :IMO Class : Class 1

## Ans 4:

Class : Class 2

one more blunder by SOF. Their Solution says answer is 20th Oct but correct answer shown is 'D' which is 27th Oct

## Ans 7:

Class : Class 2

It should be 20th October 20XX. If students of this standards get this type of mistakes then they will not be agreed to practice in this platform.

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Subject :IMO Class : Class 1