M4maths Previous Puzzles

25 Apr 2011 what will be the value of 8!

if 6! = 21
and 2! = 3
then what would be the 8!

OPtion

1) 34
2) 36
3) 40320
4) 34567
5) 87
6) 24
7) 30
8) 42
9) 96
10) 286

Solution

here 6!=6+5+4+3+2+1 = 21
so 8! = 8+7+6+5+4+3+2+1 = 36

Correct Option: 2 Best Solution (16)

~Sandeep~   14 years AGO

As per the given data, formula is n!= (n+1)*n/2
For n=8, 8!=9*8/2 = 36 (Option 2)

Like? Yes (7) | No (6)  

sanjeev   14 years AGO

6!=21 means 1+2+3+4+5+6=21
2!=3 means 1+2
8!=1+2+3+4+5+6+7+8=36

Like? Yes (4) | No (4)  

Jagat   14 years AGO

8!=sum of first 8 numbers =36

Like? Yes (4) | No (4)  

Bawa   14 years AGO

6! = 21 = 1+2+..+6=sum of first 6 positive integers
and 2! = 3= 1+2=sum of first 2 positive integers
8!=sum of first 8 positive integers =1+2+3+...+8=36

Like? Yes (4) | No (4)  

A.P.Singh   14 years AGO

if 6!=(6+5+4+3+2+1) = 21
and 2!=2+1 = 3,
then 8!= (8+7+6+5+4+3+2+1) = 36

Like? Yes (4) | No (4)  

Meena   14 years AGO

here x! = sum of first x terms.
Then 8!=1+2+3+4+5+6+7+8=36

Like? Yes (3) | No (3)  

Kalidas   14 years AGO

8! = Sigma 8 =1+2+3+...+8=36

Like? Yes (5) | No (5)  

Dr.Dipin Singh   14 years AGO

if 6! = 21
and 2! = 3

here
n! means 1+2+3+....+n
6! means 1+2+3+....+6=21
2! means 1+2=3
8! means 1+2+3+....+6+7+8= 21+7+8=36

Like? Yes (6) | No (7)  

Avinash Gupta   14 years AGO

6!=6*5*4*3*2*1
sum =6+5+4+3+2+1=21
similarly 2!=3
&
8!=36

Like? Yes (1) | No (3)  

Amit Nathani   14 years AGO

6!=6+5+4+3+2+1=21
2!=2+1=3
8!=8+7+6+5+4+3+2+1

Like? Yes (1) | No (3)  

Seema   14 years AGO

6!=1+2+3+4+5+6=21
2+=1+2=3
8!=1+2+3+4+5+6+7+8=36

Like? Yes (1) | No (3)  

dharmaveer   14 years AGO

6!=21. means we have to replace X with +. then we will get 21.
6+5+4+3+2+1 = 21

similar for 2! :- 2+1 = 3.

so 8! = 36. (8+7+6+5+4+3+2+1 = 36)

Like? Yes (3) | No (7)  

KALPANA G   14 years AGO

6!=6+5+4+3+2+1=21
2!=2+1=3
8!=8+7+6+5+4=3+2+1=36

Like? Yes (2) | No (6)  

Karthick Babu   14 years AGO

6!=6+5+4+3+2+1=21
2!=2+1=3
8!=8+7+6+5+4+3+2+1=36

Like? Yes (2) | No (6)  

Suresh Varma P   14 years AGO

1+ 2 + 3 + 4 + 5 + 6 + 7 + 8 = 36

Ans: option 2

Like? Yes (1) | No (5)  

RajiniRaja S   14 years AGO

1!= 1
2!= 1+2=3
3!= 1+2+3=6
4!= 1+2+3+4=10
5!= 1+2+3+4+5=15
6!= 1+2+3+4+5+6=21
7!= 1+2+3+4+5+6+7=28
8!= 1+2+3+4+5+6+7+8=36

Like? Yes (1) | No (5)