Number Series for SBI PO 2016

 I.Find the wrong number in the following series.

1.  40   326   2946   29418   323607

1.326

2.40

3.2946

4.323607

5.29418

2. 560   1089   1725   2443   3284   4245

1.2443

2.1725

3.4245

4.3284

5.560

3. 3252   3080   2958   2876   2826 

1.3080

2.2876

3.2826

4.3252

5.2958

4. 2442   1222   614   312   163   90   55.75

1.1222
2.312
3.90
4.614
5.163

5. 1250   1322   1452   1674   2024   2544

1.1322
2.1674
3.2544
4.2024
5.1250

II. Find the missing number in the given series.

6. 1953.125    781.25  312.5   ?   20

1.48

2.49

3.50

4.51

5.52

7. 81   87  162   504   1992   9990   ?

1.59903
2.59906
3.56895
4.59904
5.59861

8.  49   72   118   ?    394   762   1498 

1.234
2.239
3.210
4.219
5.243

9.  142   143  156   193   272   417   ?

1.653
2.658
3.659
4.657
5.656

10.  118   122   158   206   356   536   ?

1.956
2.953
3.928
4.965
5.963

Solutions:

1.2946

40*8+6=326
326*9+7=294
2946*10+8=29418
29418*11+9=323607

2.1725

the difference between numbers is +23^2 ,+25^2 ,  +27^2 , +29^2 ....... 

3.3252

the difference between numbers is -(13^2+1), -(11^2+1), -(9^2+1) , -(7^2+1), -(5^2+1)

4. 90

2442/2  + 1 = 1222
1222/2  + 3= 614
614/2   +  5  = 312
312/2   + 7 =163
163/2  + 9 = 89.5
89.5/2  + 11 = 55.75

5. 1250
  ,
the difference between numbers is +(3^3+3) , +(4^3+4) , +(5^3+5),  +(6^3+6) ,  +(7^3+7),
+(8^3+8)


6.50

1953.125/2.5=781.25
781.25/2.5=312.5
312.5/2.5=125
125/2.5=50
50/2.5=20

7.59904

the difference between numbers is  *1+6 , *2-12, *3+18 , *4-24 ,*5+30 , *6-36

8.210

the difference between numbers is  +23 , +46 , +92 , +184 , +368 ,+736

9.658

the difference between numbers is  +1^3+0 , +2^3+5 ,+3^3+10 , +4^3+15 , +5^3+20 ,+6^3+25

10. 928

the difference between numbers is 
+2^3-2^2
 +3^3-3^2 
 +4^3-4^2 
 +5^3-5^2 
 +6^3-6^2 
 +7^3-7^2 

Read Number Series trick here